family? >> was she afraid of him? >> she was afraid of him. >> i just found out they're investigating me again. >> motive outweighed everything in this case. miles away, buried in the sand, lay one piece of the puzzle. >> he said, "i know where she's at." "period." the rest of the mystery hiding away in a woman's heart. >> she couldn't keep it inside anymore. >> the killer thought his secret was safe. he was wrong. >> this is as they say a game changer? >> our prime suspect no longer has an alibi. >> i'm lester holt and this is "date line" here's dennis murphy with "secrets of the desert" >> it's a timeless old west beauty as the setting sun grazes the mountains. and the vast sonoran desert fades to dark, covering secrets and old bones for another night. it's as unchanging out here as the heartaches all those people in the valley below sometimes seem to make for themselves. with their jealousies, their rages. >> i need someone to come out and take a report, my daughter's missing. >> when daily routine, without warning, gives way to stark terror. >> she's an adult, but the back door was found unlocked. there's a broken cup at the entry way. a young woman, vanished. >> what is your name? >> i'm marilyn cox. i'm her mother. >> that was the start of it all, an anguished mother's cry for help in a case that would take 15 years to untangle. >> you didn't have a weapon, you didn't have a witness. >> that's correct >> before it was done, there'd be multiple murders. >> they pushed someone who doesn't like to be pushed. >> and maddeningly, for law enforcement, suspects who just didn't quite fit. >> the two key people had alibis. >> a daughter ensnared in a family tragedy like few others. >> did you understand what had happened? >> i don't think i really understood it, like, fully but something bad happened. >> it all started here, tucson, arizona. "the old pueblo," they call it. nestled in the desert at the foot of the santa catalina mountains. dave watson spent nearly 20 years here with the tucson fire department. he fought fires and was trained as an e-m-t. eventually he made captain. but he never forgot the camaraderie of his early days at the firehouse. >> burnin' through a lot of adrenaline together, huh? >> on occasion, yes. >> hours of boredom, moments of terror. >> yeah, pretty much. >> seemed like everything he needed. until in 1993, she came along. >> i was out with a friend, it was his birthday and met her -- at a east side nightclub, and so -- and walked up to her and asked her to dance. >> her name was linda. >> she was spontaneous, spunky, cute. and we just seemed to hit it off. >> she was very funny and very s -- just very sweet. that's always the word i think to describe her. >> marnel camp was one of linda's best friends, dave's too. she was also dating dave's best friend. the two couples soon made a young, fun-loving foursome. >> we didn't have kids yet. we didn't even have a house. you know -- neither one of us even had a mortgage yet or anything. so it was pretty carefree, looking back. >> lots of barbecuing. swimming. and, yes, a fair amount of drinking too. this was a hard-partying crowd. but there was no denying that dave and linda were in love. >> they were the ones that were well liked. cute couple. >> mike bratton was another close friend of dave's. >> the kids on the float at high school, huh? >> yeah, exactly. >> so it wasn't a surprise when in 1994, dave and linda married. >> good bash? >> yeah, oh yeah. it was a party. it was a party. >> bartender was busy that night, huh? >> oh yes, uh-huh. yes. >> dave and linda scraped together enough to money to buy their first home and take on that first mortgage. >> it was not in the best neighborhood, for sure. but very cute. it was -- had a lotta character. >> somewhere between a dump and a fixer upper? >> yeah, somewhere there. [ laughter ] >> linda and dave were up for the challenge. they worked to transform that rundown house into a loving home for themselves. and after two years of marriage, baby jordynn came along. at first dave wasn't so sure about having kids, but. >> when linda gave birth to jordynn it was just -- all that nervousness was gone. so yeah. it was nice, you know? kids make a world of difference. >> jordynn's grown up now, but remembers fine details of that little house and her mom. >> we had a strawberry patch kind of outside of the house. i remember i was picking strawberries one morning before breakfast, her cooking breakfast. >> how was linda as a mother? >> oh, she loved that little girl. that baby was her whole world. >> bobbie kutasy and pat hinkle were linda's aunts. >> she was very attentive to that little girl. loved her to pieces. >> with jordynn's arrival, dave and linda got another visitor too. >> marilyn came out to be the nanny, because they both worked. >> marilyn, was linda's mother. >> was that an sos that went out from linda to marilyn to -- >> yes. >> to come? "mom, co -- i need some help here." >> yeah. yeah. exactly. >> not an unusual request from a new mother but marilyn's response was unusual. >> she sold her house and drove her car and headed out to take care -- >> she did all that for her girl and her granddaughter. >> she did that for the -- for the family. >> and -- and where was she living? >> d -- dave actually built a little -- a little guesthouse out back for -- specifically for marilyn. >> not every young husband likes to have the mother-in-law around, let's face it. >> it's funny that, you know, all the guys at work said, "ah, that's a big mistake." [ laughter ] they said, "it's gonna end up in divorce." >> what was she like? >> very pleasant, polite and -- but as time went on -- you know, you live with somebody for 24 hours at a time, you get to know more about 'em and-- our relationship got strained. >> and soon that wasn't the only relationship suffering. linda's friend marnel, who by then was married and living in oregon, noticed the change when she invited dave and linda up for a visit. >> you were seeing the cracks right before -- >> absolutely. absolutely. yeah. >> coming apart was a hard reality for dave to accept. >> i had planned on stayin' married forever, you know? that was the deal. but it just didn't turn out that way. i was no more -- longer in love, but i still loved her. you know, and she's the mother of my child. >> in 1998, dave and linda separated, sharing custody of jordynn. that same year, dave met someone new. >> i saw him and his buddy and i nudged my friend and i said, "i'm gonna go ask him to dance," and i made a beeline. >> her name was rosemary and she ran a successful karaoke business in town. >> she's quite an entertainer, i guess, huh, rosemary? >> yeah, she is. she says, "if you wanna be successful in this business you -- you know, you gotta sell it." >> they fell for each other hard and fast. their shared love of music. the outdoors. and little jordynn. >> he loves jordynn very much. i know when i met him, he definitely had, you know, parenting time with her. and it would go back and forth between linda and dave. >> rosemary also had a daughter from another relationship. and in june 2000, she and dave took the big step of blending their families. >> i had my daughters by my side. he had his two good buddies. and we took our vows and celebrated with everybody around us. >> linda also seemed to find happiness in a new relationship. his name was carl barton, junior. though most people knew him as j.r. he was a firefighter too. for the air national guard in tucson. >> what'd you think? >> he seemed nice. you know, i met him a handful of times but more than -- skin-deep i didn't know much about him ever. >> linda called marnel and gushed about her new flame. >> he was older. and i remember -- her commenting about how, you know, he was sexy or something like that. >> marnel, busy juggling family and career, really didn't pay close attention. if her friend was happy, then so was she. until the phone rang one morning in august 2000. >> this phone call -- >> i think was one of the lines in the sand where your life was different thereafter. >> absolutely. changed there. everything changed from there on out. and just got uglier and uglier. >> on the phone -- linda's mother. with a question. when we return... >> she said -- "marnel, it's marilyn, and is linda with you?" >> with you? why would she be with you? >> it was the strangest call of my life. but things would soon get much stranger. >> we got there, her car was there, and she wasn't home. lk through our front doors. and you inspired our new flavors. introducing mcdonald's signature crafted recipes. sweet barbecue bacon made with crispy onions. pico guacamole made with real hass avocados. maple bacon dijon with thick-cut applewood smoked bacon. purchase any signature crafted recipe sandwich and use the mcdonald's app to get a free medium fries and soft drink. you bring your flavor to the world... we bring ours to you. ♪ whether you dry, curl or straighten you can visibly repair 7 types of damage with tresemmés new repair and protect 7 with biotin tresemmé puts in the work so you can work it new neutrogena® rapid wrinkle repair wrinkles? your time is up! with the proven power of retinol. reduces wrinkles in just one week. neutrogena® nosy neighbor with a glad bag, full of trash. what happens next? nothing. only glad has febreze to neutralize odors for 5 days. guaranteed. even the most perceptive noses won't notice the trash. be happy. it's glad. and i used to ask if you could hear me now, with verizon, but i switched to sprint. hey... are you happy that you switched? yes - their network reliability is within 1% of verizon and our unlimited plan is half what you pay with verizon for a family of four. half? that's right - it's half. you could save over $1000 in the first year! they've been ripping us off! just think what you could do with that money. i'd buy a new set of golf clubs. vacation. (vo) unlimited! $22.50 per month per line. that's 50% off verizon unlimited rates. for people with hearing loss, don't let a 1% difference cost you twice as much. visit sprintrelay.com. >> reporter: the week of august 21, 2000, started out like any other, until marnel camp's phone rang. it was marilyn, her friend linda's mom. >> she called and said, "marnel, it's marilyn, and is linda with you?" and -- >> reporter: with you? why would she be with you? >> it was the strangest call of my life. >> reporter: marilyn said she and linda had gone to church sunday evening. the next morning, marilyn couldn't find her. how'd she sound -- >> said -- >> reporter: -- marilyn? >> very stressed. very stressed. >> reporter: marilyn also called the pima county sheriff. >> she's an adult, but the back door was found unlocked. there's a broken cup at the entry way. >> reporter: detective kelly anderson wasn't on the case back then, but remembers it well. >> there are not that many adult missing persons because, frankly, an adult can go wherever they want to. and they don't need permission or they don't have to tell anybody. >> reporter: still, a deputy was dispatched to linda's house. >> he doesn't see anything that would indicate foul play -- >> reporter: nothing's been tossed in the house? >> no. he doesn't see any blood, any indication of -- of violence or a struggle. the only thing he notices is the broken coffee cup and some property that linda has left behind that may be a little suspicious. >> reporter: linda's bible was on the counter. her jeep in the driveway. and, perhaps most telling, she left her pager behind. remember, this was 17 years ago. >> when she didn't have her daughter, she would keep her pager so that if anything happened with her daughter that was the way to communicate with her. >> reporter: so this is important. that's a link to the daughter. >> that's a link to the daughter. >> reporter: doesn't mean anything's happened here yet though. >> not yet. her purse is gone. so the deputy tells miss cox, "let's just wait." >> reporter: marilyn didn't want to wait. she called her younger sister pat. >> she tells me, "pat, linda's missing." of course, you know, this don't happen to your family. it happens to other people. >> reporter: marilyn also called linda's ex-husband, dave. >> marilyn says that linda's not home, she's missing. she sounded panicked and it was like, "give us some time. it's monday morning. maybe she went somewhere." >> reporter: three days passed. it was linda's turn to take jordynn. dave and then 4-year-old jordynn drove to linda's house. >> we got there, her car was there, and she wasn't home. and so, you know, he was, like, "oh, that's weird," you know. "she's probably just out with a friend or something." >> reporter: it didn't sound that farfetched to many people who knew linda. >> she always liked to party. and supposedly she had a couple relationships with some crazy people and -- >> reporter: hop in the wrong truck after a night of drinking? >> maybe. yeah. the -- that was the assumption at the time. >> reporter: investigators continued to poke around anyway. they wanted to talk to linda's boyfriend, j.r. marilyn brought him up when she reported linda missing. >> does he live near there? >> no. he lives over at silverbell. >> reporter: silverbell road. a two-lane blacktop that meanders from tucson out into the vast desert. a detective went to j.r.'s home. >> he cooperated in every way that was asked of him. >> reporter: j.r. told the same story others did -- that linda was a heavy drinker. >> we had a seriously rocky relationship for over two years. all about -- all of our problems revolved directly around her alcoholism. >> reporter: the drinking was why, j.r. said, he recently broke up with linda. >> she wigs out bad and things right now are rougher than i've ever seen 'em for her, you know? she just lost her job. >> reporter: he said too much alcohol cost linda her job. and, j.r said, linda faced an even bigger loss. >> she's lookin' at losin' her daughter. >> reporter: turns out linda and dave hadn't yet come to terms on custody of jordynn. and they had an important court hearing coming up. are you going for full custody? >> i didn't want to take all the rights away from linda, by no means, 'cause you know, every child needs both parents. >> reporter: but after his break up with linda, j.r did something unexpected. he volunteered to testify at the custody hearing -- on dave's behalf. so here's a strange thing -- he now has your back in family court? >> not so much mine. i'm sure he could give two shakes about me. but he cared about jordynn so he was doin' it for her, not me. >> reporter: more pressure on linda. she had joined a 12-step program. still, shortly before she disappeared, she went out drinking with her cousin jay, pat's son, at a place away from the bright lights of tucson -- a bar called the circle s saloon. >> jay was over there and -- and she was needing to get around some family 'cause, you know, things was a little tough for her, so s -- he told her, "well, come on out." >> reporter: linda tried to climb back on the wagon. about 10:00 p.m. the night she disappeared, she called her church sponsor and asked to meet the next morning. but she didn't show up for the meeting, and hadn't been seen since. there seemed to be every reason to believe she was on another bender. except for one thing, something marilyn mentioned in that initial 911 call. >> yeah, he's threatened her before. he's threatened me, too. >> coming up -- and had linda asked for help a little too late? >> it's linda. he was over here this morning beating on my windows. calling me. i need to know, should i go down and put a restraining order on him? >> when "dateline" continues. and i couldn't wait to get my pie chart. the most shocking result was that i'm 26% native american. i had no idea. just to know this is what i'm made of, this is where my ancestors came from. and i absolutely want to know more about my native american heritage. it's opened up a whole new world for me. discover the story only your dna can tell. order your kit now at ancestrydna.com. anyone can get you ready, holiday inn express gets you the readiest. because ready gives a pep talk. showtime! but the readiest gives a pep rally. i cleared my inbox! holiday inn express, be the readiest. heare you one sneeze away from being voted out of the carpool? try zyrtec® it's starts working hard at hour one and works twice as hard when you take it again the next day. stick with zyrtec® and muddle no more®. a 10-speed direct-shift 5.0transmission.ine. a meticulously crafted interior. all of these are feats of engineering. combining them with near-perfect weight distribution... ...is a feat of amazing. experience the first-ever 471-horsepower lexus lc 500 or the multistage hybrid lc 500h. experience amazing. here at home. james comey will appear before the senate intelligence committee and testify as part of an investigation into russia )s interference in the election. we )ve just posted that story on our website. =add= ands here comes the heat chief meteorologist jeff rainieri just tweeted an >> reporter: before she disappeared, investigators learned linda watson was facing the most trying time of her life. >> she was broken up. she was upset at jr. she was going through a -- a custody battle. >> jr told detectives the custody issue was weighing heavily on linda. >> she's told me more than once that -- and this is the scary thing, if she lost her daughter she would shoot herself. >> reporter: so jr said. linda's mom shared her doubts with her sister pat. >> what did marilyn think about this guy, jr, the boyfriend who's in and out of the picture? >> she didn't like him. she said that he's very controlling. >> reporter: which is why when marilyn couldn't find linda. her mind immediately jumped to j.r. that very first day, she told her suspicions to the 911 operator. >> she's been threatened by this guy that she broke off with. i called him. i said, "where's my daughter?" >> reporter: investigators learned that after marilyn called j.r. to ask about linda, j.r. called linda's attorney from her custody case and left this message. >> she's probably out on a drunken binge and her mom is blowing this all out of proportion. you know, i had nothing to do with anything. i don't know what to do. i thought -- i was hoping maybe you knew where she is. >> reporter: he phoned someone else as well. >> he called me up, told me that marilyn had called him, accused him, blamed him and asking, you know, "where's my daughter?" >> reporter: was j.r. protesting too much? detectives learned, while he was dating linda j.r. sometimes went with her to pick up or drop off jordynn. that's how he knew dave. >> he was also a firefighter. he had met dave not through fire-fighting. but while he was, linda doing child custody exchanges of jordynn he had met david and rosemary watson at that point. >> reporter: rosemary, dave's new wife of two months. >> keep your eye on that name. >> keep your eye on that name, yes. >> what is j.r.'s alibi for the night that linda goes missing? >> on the night that linda went missing, j.r. was with his girlfriend. >> reporter: his new girlfriend. jr was already moving on, he said, but he still seemed concerned about linda. >> jr was very helpful, offering different ideas or people to talk to. >> but i think cynically sometimes, detective, guys inveigle themselves into an investigation when, in fact, they're part of the -- the scheme. >> sure. that-- that could certainly happen. >> reporter: detectives also had more concrete reasons to suspect j.r. >> there was a domestic incident that they were involved in shortly prior to this. >> reporter: just two days before linda disappeared. she had called the pima county sheriff's department. >> she made a report that j.r. had come to her house on curtis and was banging on the windows and banging on the doors. >> reporter: j.r. said he was just trying to pick up some of his belongings. but it prompted linda to call her attorney the weekend she disappeared. >> hey, david. it's linda. j.r. will not leave me alone. he was over here this morning, beating on my windows, calling me. i need to know, should i go down and put a restraining order on him? >> reporter: she wasn't the only one. rosemary and dave also had a restraining order against j.r. it stemmed from an incident when he was still dating linda and came to pick up jordynn at their home. >> i was home alone with the kids, and just, you know, banging on the door, the big, heavy -- not just a knock, knock. it was kind of, you know, a boom, and it was more his tone at the time. it made me nervous enough to protect myself and the kids and everybody involved. >> reporter: of course after j.r. and linda broke up, things changed. >> j.r. came to us and said that he had concerns for linda and her drinking, and he said that he would testify about her drinking in order to protect jordynn. >> reporter: the hearing happened right on schedule, just four days after linda disappeared. dave and rosemary were there, of course, j.r. too. linda was still nowhere to be found. but her mom arrived, spoiling for a fight. >> reporter: j.r. was in the courtroom and she accused j.r. of harming her daughter. >> she thinks this is foul play? >> yeah, she does. >> reporter: with linda a no-show, the judge awarded temporary full custody of jordynn to dave. >> were you happy with that? >> oh, i was definitely happy with jordynn in my life, yes. >> reporter: marilyn went back to linda's house dejected, but not defeated. and that's when she made a discovery that changed everything. coming up. marilyn calls us and said that she found blood in the entry way to linda's house. now we have a theory of foul play. >> reporter: but what police didn't have was a suspect. >> the only two people that might be looked at both had alibis. (burke) at farmers, we've seen almost everything, so we know how to cover almost anything. even a coupe soup. [woman] so beautiful. [man] beautiful just like you. [woman] oh, why thank you. [burke] and we covered it, november sixth, two-thousand-nine. talk to farmers. we know a thing or two because we've seen a thing or two. ♪ we are farmers. bum-pa-dum, bum-bum-bum-bum ♪ this blue goo leaves a residue quit playin' with my eyes,ghter. goo... so, seventh generation developed this powerful natural detergent it gets your clothes clean. really clean. buh bye blue goo, and come clean with seventh generation. it can struggle with large debris and stuck-on dust. at shark, we asked, "what if the vacuum head can do more?" so we removed the front wall and added a rotating soft brush. so while deep-cleaning carpet, you can also grab large particles, even pull in piles... ♪ ...and directly engage floors for a beautiful, polished look. shark duoclean. invented to help you do more on carpets and floors. i've gotta hit the loo. we can't stay here! why? terrible toilet paper! i'll never get clean! way ahead of you, big daddy. aww. (avo) charmin ultra strong. it's washcloth-like texture helps clean better. it's four times stronger and you can use less. beautiful view. thanks to charmin. and you, honeybear. awwwww. (avo) we all go. why not enjoy the go with charmin? >> reporter: linda watson had just vanished. she didn't even show up to a custody hearing involving her four-year-old daughter jordynn. did you feel abandoned, jordynn? >> no, not really. my dad was always right there if i needed anything. >> reporter: linda's mother, marilyn, however, was very worried. especially when she returned to linda's house after the custody hearing. >> marilyn calls us and said that she found blood in the entryway to linda's house. >> reporter: the blood was under a trash bag, hidden from view. the deputy who responded to marilyn's 911 call hadn't seen it. now investigators came back and did a luminol test. >> it -- it lit up blue and turned out to be positive for not only human blood but matching dna to linda watson. >> reporter: now that they were looking for blood, they found more, on the vacuum cleaner cord. >> it was apparent from the blood pattern that it wasn't dripped, it wasn't smeared, it wasn't wiped. it -- the cord had been laying in a pool of blood to get that pattern and then dried. >> reporter: did all these little fragments of observations suggest a narration, detective? >> something violent happened in this area. someone had cleaned up. >> reporter: so now you have a theory of foul play to explain her disappearance. >> now we have a theory of foul play. >> reporter: were investigators looking at j.r. as a potential suspect? >> he was certainly looked at as a person of interest, mostly because marilyn said, "this guy coulda done it." >> reporter: but j.r. also had a defender, linda's ex-husband, dave. >> would you personally feel if j.r. would be somebody that could do something he's being accused of? >> no i -- i strongly believe he -- he didn't do a thing. um, he's the only one that's tried to help her, and marilyn's the one pointing her fingers at him. >> reporter: of course, investigators had to wonder. after all, j.r. had backed dave in the custody dispute with linda. could dave be covering for him now? for that matter, where was dave the night linda disappeared? >> from what time to what time were you -- were you home? >> sunday, i was here all day long. >> and you never left jordy or -- or your other daughter in anyone else's care? you were -- pretty much took care of 'em all day and all night? >> yeah. >> reporter: the detective also interviewed rosemary, dave's wife. >> i have a karaoke dj business, and sunday night, i was working. >> reporter: dave, she said, was home with the kids. >> so you got home about 1:00 or 1:30, and he was home. >> yes. he was sound asleep. >> reporter: so both dave's wife and j.r.'s girlfriend said the two men were at their own homes the night linda disappeared. and despite all that blood, there was still no conclusive proof linda was even dead. >> we have no body. we have no evidence of anything outside of the entryway. and certainly the only two people that might be looked at, the ex-husband and the ex-boyfriend, both had alibis. >> reporter: the investigation had stalled, and linda's case landed in the place no victim's family wants. >> it's the vault. >> reporter: and what is that? >> our administration building, many years ago before we occupied it, was a bank. and on the second floor there is an actual vault. and that is where we keep the cold cases. >> reporter: locked away. a tomb of sorts where mysteries lay buried and forgotten. but linda's mom would not forget, would not give up. >> i wanna find her. if nothing else, i wanna take her home. i don't want her in this desert, i want her to go home. >> reporter: that sprawling sonoran desert. what secrets could it be hiding? marilyn paid for billboards, raised reward money, organized vigils. this was the start i think of what you would come to regard as the steel strength of marilyn. >> absolutely. yeah. >> reporter: and even if she couldn't find linda, she would continue linda's fight for jordynn. >> marilyn sought a lawsuit for grandparents' visitation rights. >> reporter: marilyn filed a lawsuit seeking unsupervised visits with her granddaughter. she made her case in court, and in the media. >> i owed it to linda and i owed it to jordynn and i owed it to myself to, um -- do as much as i could. >> reporter: dave and rosemary fought back, for fear of what marilyn might say or even do to little jordynn. >> she's flat out told me that as soon as she gets lin -- finds linda, gets jordynn, she's leaving this god forsaken place. >> reporter: amidst their legal dispute, dave and rosemary grew their family. in 2001, they had a little boy, caden. and then a year later, rosemary took a bold step and adopted jordynn. >> i sent out -- [ laughter ] i sent out birth announcements. i said -- >> reporter: did you? >> "it's a girl," you know. "three foot two, whatever, 68 pounds," kinda thing. i was ecstatic. >> reporter: for jordynn, the feeling was much more muted. >> it seemed like what my father wanted to happen. i didn't wanna displease anybody, so i just said yes. [ laughter ] >> reporter: with three kids, the court battle, and work, the watsons had their hands full. but dave always made it a point to check in with jordynn. >> when i was little, and even now -- you know, when he goes to work still i -- i kind of worry. >> reporter: to calm her nerves, dave made sure to tuck her in every night. >> even if he's at work, he'll still call and say goodnight around the same time every night, just in case -- >> reporter: does he still do that? >> yes, he does. >> reporter: last night you got a tuck-in call from him? >> uh-huh. i did. [ laughter ] >> reporter: in january 2003, two and a half years after linda vanished, the court finally issued a ruling. marilyn sent linda's friend marnel an email with the news. >> in big, bold letters she wrote, "i've got jordy." >> reporter: after a two-year legal battle, marilyn won the right to have unsupervised visits with jordynn. >> i always thought that linda must be -- must've given her a little bit of peace to know that jordynn was with her mom. >> reporter: rosemary and dave were not happy. rosemary spoke to nbc affiliate, kvoa-tv, after the ruling. >> not the state's place to decide where my children stay. they're turning parents into babysitters. >> reporter: at first marilyn said the watsons resisted the judge's order. >> she attempted to have her visitation but dave watson made it difficult by not answering the phone, by not being available. >> reporter: marilyn took them back to court for contempt, and once again, she won. on may 7, 2003, marilyn was due to have her first unsupervised visit with now-seven-year-old jordynn since the contempt hearing. do you remember seein' jordynn off that day? were you off-shift, or --? >> oh yeah, i was off-shift, yeah, yeah. booted her out the door. >> reporter: "have fun," huh? >> yeah. >> reporter: marilyn and jordynn spent the day together. do you remember what you all did that day? >> i don't. i don't remember that day. >> reporter: maybe the movies? maybe some shopping? >> maybe something like that, but i don't remember it. >> reporter: maybe not. but what happened next was unforgettable. >> coming up -- >> i -- i said, "is -- is that my sister?" and he said, "yeah." and i said is she dead? and he said yeah. >> lightning strikes twice. >> reporter: how quickly, detective, do you start to connect the dots? >> immediately. >> when "dateline" continues. where's the rest of it? uh, the soy sauce? it's gone. treat your clothes better with new tide pods plus downy. it's got to be tide "for great skin, you don't have ...just go to bed." new aveeno®... ...positively radiant® overnight facial. get the benefits of a spa facial... ...overnight. aveeno®. "naturally beautiful results®" ♪ whatever it is that floats your boat... ...or tickles your tastebuds... ...or brightens your day... ...even if you've never tried it before... ♪ ...just know that... you can, in portland. ♪ whatever it is that floats your boat... ...or tickles your tastebuds... ...or brightens your day... ...even if you've never tried it before... ♪ ...just know that... you can, in portland. reporter: may 7th, 2003. linda and marilyn's friend marnel camp had just moved back to tucson. she made plans to catch up with marilyn, who was elated at just having been awarded unsupervised visits with jordynn. what were the plans with jordynn? >> just to stop at the house and see her and see jordynn. and then possibly go with her to take jordynn home. >> reporter: but by the time marnel made it over to the little house on curtis road -- >> i drove into the driveway at 7:00 -- about 7:45. and it was dark. nobody was there. >> reporter: marnel must have just missed marilyn, who was supposed to have jordynn back at dave and rosemary's home by 8:30. >> after about ten minutes or something, i thought, "i'll just write her a note, put it on the door." and i didn't have any paper, so i didn't. >> reporter: that's when marnel remembered something -- a tv appointment. >> i thought, "oh, if i leave now, i can still catch the bachelor." >> reporter: just a short while after she left -- calls started pouring into pima county's sheriff's dispatch. >> they're -- they're shot. somebody's been shot. >> and there -- you said there's two people on the ground? >> yes. someone ran away. in a black sweater with a hood on. >> reporter: marilyn's sister pat was just getting ready to turn in when the tv caught her attention. >> it was the 10:00 news and right at the -- you know how they roll something across there? it said, "two ladies shot on curtis road." >> reporter: marilyn's street. pat rushed over and found an active crime scene. she saw an officer she knew. >> i said, "is -- is that my sister?" and he said, "yeah." and i said, "is she dead?" and he said, "yeah." and i asked him, "will you please let me go to her?" and he says, "no, i can't let you do that." and so i just, kind of, what could i do? i just lost it there. >> reporter: it was nearly incomprehensible. two tragedies in the same family. first, linda disappeared. now, marilyn, having just returned home from dropping jordynn off, murdered. >> and renee also. renee was an innocent little neighbor lady, you know? she was just doing marilyn a favor. >> reporter: renee farnsworth, the second victim, marilyn's friend and neighbor who had gone with her to drop jordynn off. renee's daughter, dorothy, pleaded to the public for help. >> i'm here for my mom. i hope that somebody out there has it in their heart to come forward and help us with this. >> reporter: someone had ambushed the two women in the driveway. renee had been shot once. marilyn twice. the second shot at close range to the head. >> reporter: do you have crimes like that in tucson in that neighborhood? >> i'm a homicide detective. i wouldn't need this job if we didn't have any homicides. and how nice would that be? but this is incredibly rare to have a random act of violence to two women who have done nothing to anybody. >> reporter: how quickly, detective, do you start to connect the dots and say, "this is the mother in the same house of the missing linda watson?" >> immediately. immediately. >> reporter: several hours later, pima county sheriff's investigators went to the last place the two women had visited. >> two detectives came over and had told us they were there to do a well check on jordynn. and they started talking to us. >> reporter: investigators told them there had been a shooting at marilyn's home. they wanted to know where the watsons had been. >> when she dropped her off, you and your wife were here, right? >> yeah. yeah. >> okay. >> i had a union meeting. i came home. um, i got home about 8:15 -- 8:10. 8:15. um, jordynn came home about 8:30. >> reporter: the investigator asked if they had any contact with marilyn. >> you ever make any contact with her at all? >> she pulled up, um, and i -- i was in the restroom. >> reporter: so dave said rosemary came to the door. what does she make of what's goin' on? >> same as me, just -- she's kinda speechless, not -- just kinda takin' it all in, tryin' to process it all. >> reporter: the investigators never told dave and rosemary exactly what happened that night. dave said it wasn't until the next day that he saw the news and learned that marilyn had been murdered. did you feel bad about marilyn? >> oh heck, yeah. i mean, yeah. i mean, how could i not? this is jordynn's grandmother. >> reporter: there was someone else detectives needed to talk to, j.r., linda's ex-boyfriend, who marilyn had accused of murdering linda. >> where were you on 7th may 2003, uh, between the hours of approximately 1800 and 2100 hours, if you could recall? >> i was at home. >> reporter: j.r. told investigators he spent the evening with his fiance and his kids. and for some reason he felt the need to tell marilyn's family, too. >> i got a call the next morning from j.r telling me he had an alibi. i said what do you need an alibi for, j.r.? "well, i just wanted you to know." and i said, "okay. bye." just hung up. >> reporter: the dawn had risen on the longest day of their lives. marilyn, the matriarch of their family, the one who fiercely fought to keep linda's case alive, was gone. for family friend marnel the heartbreak was two-fold. >> i didn't realize until then that i never truly let go of the idea of linda coming back until marilyn was killed. and that's when i realized, oh, she's gone. that's -- she's dead. and -- >> reporter: so this is a double nightmare? >> yeah. >> reporter: had you agreed to take jordy home for the drop off, you really would've been in this. >> most likely, yeah. >> reporter: three years after linda's disappearance, investigators had a whole new, deadly mystery and the key to unlocking it just might be a voice from the grave. coming up -- did marilyn know what was coming? >> she said, "and that's a gun laying right there. i won't be as easily taken as linda was." introducing listerin® zero alcohol™. it delivers a whole mouth clean with a less intense taste. so it has the bad breath germ-killing power of this... [rock music] with the lighter feel... of this. [classical music] for a whole mouth clean with a less intense taste... ahhh. try listerine® zero alcohol™. also try listerine® pocketpaks for fresh breath on the go. quin was crazy about curls. but it took a twist of fate to find a high-end curler at such a head turning price. and that's the beauty of a store full of surprises. you never know what you're gonna find, but you know you're gonna love it. ♪ haribo sour goldbears? oka- yeah! so who wants some they taste a little sweet and sour. fizzy. fizzy. these bears are dancing on my tongue. umm, this is ice hockey, not dance party. ♪ kids and grown ups love it ♪o ♪ the happy world of haribo ♪ ♪ sweet cinnamon-sugar on the outside, crazy on the inside. crave those crazy squares. introducing mcdonald's new like the sweet barbecue bacon signature crsandwich.ipes. tangy barbecue sauce made with sweet onions. thick cut applewood smoked bacon. and topped with crispy, golden onions. on chicken or seared beef. (vo)well, it's not one look.... ethan allen is about the freedom to design your look. free shipping, free delivery and up to 20% off everything. design your look today. you'll be amazed what happens when you pu♪ your red nose on. you help ensure that children in the u.s. and around the world are safe, healthy and educated. this red nose day, swing by walgreens and get your noses on to help end child poverty. walgreens. at the corner of happy and healthy. >> reporter: for years marilyn cox had been an advocate for her missing daughter linda. with marilyn's murder, that role fell to her sister pat. >> i felt like literally she handed me the baton. and i told her "you know, i might not do as good a job as you, but as long as there's breath in me, i will do my best to try to find linda and i will try to find who killed you." >> reporter: pima county sheriff's detectives were working to do the same. for marilyn's family and for the family of renee farnsworth. >> renee is as much a victim as anybody else. >> she was moral support, huh, for her friend. >> she was in the wrong place at the wrong time. >> reporter: investigators compiled the preliminary evidence from eyewitness accounts. >> we know as soon as they got out of the car they are attacked, accosted by a lone gunman, six feet to 6'2", slender, well-built, something covering his face, probably a hoodie. >> reporter: it looked like a targeted killing. >> there's no other motive. there's no burglary, there's no sexual assault, there's no car theft, there's nothing. >> reporter: but there was potentially valuable physical evidence. >> the bullet casings from the scene were a -- nine millimeter. and when you combined the bullet casings with the bullets from the victims it was consistent with a ruger nine millimeter p85, semi-automatic handgun. >> reporter: hanging over everything was the question, who would have wanted marilyn dead? detectives knew from the moment linda disappeared. marilyn had accused linda's ex-boyfriend, jr, of harming linda it became a nasty feud. they even tried to get restraining orders against one another, but a judge denied their requests. which is when marilyn's attention seemed to shift. >> after about january of 2001 when j.r. and her had no more contact with each other. and she totally focused on dave. >> reporter: detectives knew. the whole town knew, that marilyn had been feuding with dave and rosemary over visitation with jordynn. pat said the reason marilyn asked her friend renee to go with her to drop jordynn off was that she feared a confrontation with dave. >> she thought it -- there was safety in numbers. >> reporter: pat recalled an earlier incident, she said, when she was on the phone with marilyn, and dave showed up unannounced at marilyn's house. >> she let him in the house, which just blew me away. she wanted him to feel better at having jordynn over there, so he could see that it's nice, it's not dangerous, and i'm not planning on taking off. >> reporter: but, pat said, the visit turned tense. >> so she showed him through the house and took him towards the little bedroom and it was just off to the left there, and she said, "and that's a gun laying right there. i won't be as easily taken as linda was. >> reporter: linda warned everyone around her, that if anything happened to her, there was one person they should look at. this is a letter she wrote to the sheriff's department in february 2003, shortly after she won the visitation case. and just months before she was murdered... >> this is just to let you know that if i should suddenly disappear that i am not on vacation as they told jordynn linda was. i hope you keep this on file somewhere because dave has now lost some major control and he's having a hard time with that. >> she was nervous and she was scared of david watson. >> reporter: of course, investigators had already questioned dave. and for good measure j.r. as well. but once again, they both had alibis that checked out. so did rosemary. she had been at home with the kids when marilyn dropped jordynn off. >> ever look at rosemary as a co-conspirator here possibly? she had interest in retaining custody of the child, too. could they have been in on it together. >> sure. you don't ignore the wife just because she's who she is doesn't mean that she's excluded as being looked at. obviously, she's not a man running from the scene. we know that. but could she be involved in it? could she be planning it with him? >> reporter: detectives had already talked to rosemary, of course. but there was another potential witness at that house. what did she know? >> coming up -- >> how old are you, jordynn? >> seven. >> seven years old. my goodness. you're growing up so quick. >> jordynn tells her story, and suddenly david watson's story looks a little less solid. >> she does not know where dad was at 8:30. >> when dateline continues. i was a doer. i was active. then the chronic, widespread pain drained my energy. my doctor said moving more helps ease fibromyalgia pain. she also prescribed lyrica. fibromyalgia is thought to be the result of overactive nerves. lyrica is believed to calm these nerves. woman: for some, lyrica can significantly relieve fibromyalgia pain and improve function, so i feel better. lyrica may cause serious allergic reactions or suicidal thoughts or actions. tell your doctor right away if you have these, new or worsening depression, or unusual changes in mood or behavior. or swelling, trouble breathing, rash, hives, blisters, muscle pain with fever, tired feeling, or blurry vision. common side effects are dizziness, sleepiness, weight gain and swelling of hands, legs and feet. don't drink alcohol while taking lyrica. don't drive or use machinery until you know how lyrica affects you. those who have had a drug or alcohol problem may be more likely to misuse lyrica. with less pain, i can be more active. ask your doctor about lyrica. lergies with nasal congestion? find fast relief behind the counter with claritin-d. [ upbeat music ] strut past that aisle for the allergy relief that starts working in as little as 30 minutes and contains the best oral decongestant. live claritin clear, with claritin-d. >> reporter: continuing our story. >> we all knew there's something very wrong here. what were the odds? first, a young mother goes missing. >> it became very clear that linda wasn't coming back. three years later, her mother is murdered. >> how often are a mother and daughter killed at the same house. >> it seemed like there had to be a link. but what was it? >> there is a lack of physical evidence in this case. one person knew the truth. >> when you have a deep dark secret, you don't tell people. but soon, someone would. >> all of a sudden, i just couldn't breathe and i said, "oh my god, this is it." >> reporter: here again is dennis murphy. three women, gone. in 2000, linda watson disappeared from her tucson home. leaving little more than traces of blood and a broken coffee cup in her wake. three years later, linda's own mother, marilyn. who'd fought for answers for justice for her missing daughter. gunned down with her friend renee in the driveway of that very same home. detectives couldn't dismiss the strange coincidence of two tragedies happening at the same place. to the same family. >> how often are a mother and daughter killed at the same house three years apart? that doesn't happen. >> reporter: when linda went missing, two men were blips on the investigators' radar. first was her ex-boyfriend, j.r. with whom she'd had a tumultuous relationship. j.r. insisted he was at his house the night of marilyn and renee's murders. and his alibi checked out. plus, said detective kelly anderson -- >> there's nothing evidentiary at the scene that would indicate j.r. had any involvement. and he doesn't even match the physical description of the person the eyewitness saw at the scene running away. >> reporter: but then there was linda's ex-husband, david watson. he too, of course, had an alibi. he said he was home the night of the murders and his wife rosemary backed him up. but investigators were eager to speak with someone else at the house that night. a small child facing a very grown-up tragedy for the second time. >> how old are you jordynn? >> seven. >> seven years old. my goodness, you're growing up quick. >> reporter: dave's daughter, jordynn, sat down for an interview the day after her grandmother was killed. she told the detective that her adoptive mom rosemary greeted her at the door when marilyn dropped her off at home. >> where was your dad when you got home? >> he was outside. >> and how do you know that? >> he came in and-he told me. 'cause, i remember that he was still at a meeting. >> reporter: a curious response from the little girl. that dad "told" her he'd been outside. >> he just came in the bedroom to say goodnight. >> reporter: the detective prodded further. >> when you came home and your mom let you in, did you ask her, you know, is dad here? or where's dad? did you want to see your dad? >> yeah. >> okay. did you ask her anything about that? >> yeah. she said, "i don't know." >> okay. tell me exactly what you asked her, as best you can remember. >> i said, "is dad still at his meeting?" she says, "i don't know." >> she does not know where dad was at 8:30. >> reporter: detectives wanted to speak with dave watson again. >> did you think, "i'm in trouble here? these guys are lookin' for me for this thing?" >> no. no. i just figured they just -- checkmark on their list of people to go talk to. >> reporter: once again, dave told the detective he was home from his fire department meeting by the time jordynn arrived at 8:30. remember, though, the night of the murders, he said he was in the bathroom when jordynn was dropped off. now, his story was a little different. >> i'm out there messing with the dogs so i was out back. >> reporter: small inconsistencies. but detectives also wanted to ask about their strongest piece of evidence. bullets and shell casings consistent with a 9-millimeter ruger handgun. did dave own that type of gun? >> you still have a ruger? >> the ruger? no, i sold that during the divorce. yeah, i needed the quick cash. >> who'd you sell it to? >> uh, [ bleep ], i dont even know. it was -- coworker, or somebody off the street, or --? >> no. off the street. put an ad in the paper. >> well, we ended up looking for that ad, and we were never able to find any ad for a nine millimeter by dave watson. >> reporter: but when they looked in dave's gun safe, they did find 9-millimeter ammunition. why would he have that, if the gun was long gone? they asked the big question. >> and to be point-blank, did you kill marilyn cox? >> no, i did not. >> did you have any reason to kill renee farnsworth? >> no. >> detective do you know where linda watson is, or what happened to her? >> no, still don't. >> reporter: a firm denial. and they had nothing that placed dave at either crime scene. and detectives talked to rosemary again, who confirmed what she'd said initially. >> what time of night do you think he got home? >> i didn't look, but it was shortly before jordynn came home, so i'm gonna -- it was either, like 8:15, 8:20-ish. right in there. >> reporter: which meant dave could not have been the shooter. but then, a few weeks after marilyn's death. her sister bobbie kutasy noticed something in marilyn's backyard. >> as i'm coming back toward the gate -- a reflection caught my eye. >> and i said, "look -- look at this. look what i found." and i picked it up and it still -- i think i said, "somebody lost their money clip." and it said, "ddw." >> anybody you know is a "ddw?" >> well, we know dave watson. and his middle name is dwayne. >> reporter: there was no proof it was dave's. no fingerprints or dna. and even if it were dave's, it didn't necessarily mean anything sinister. after all, he'd once lived in that home. except -- >> after linda's disappearance marilyn got rid of everything that remained of dave's. and by every account anything that belonged to dave was long gone. >> so what do you make of the initial money clip? is it evidence? just something maybe interesting or what? >> no it's beyond interesting. that's certainly evidence. "ddw" goes beyond coincidence. >> reporter: and there was something else. an unusual comment dave's friend, mike, overheard. >> dave allegedly says -- somebody brings up -- marilyn's murder in the driveway. he says, "well, i don't know what happened, but she probably deserved it." >> i -- i did hear him say that. i don't think that was -- a good comment, neither. i mean i don't have an answer to that. didn't-- don't like to hear sumpin' like that about anybody. but that was him saying it. >> reporter: bad blood. contradictory statements. shell casings and a money clip. >> i -- i imagine in your war room in the homicide offices or you're -- you're batting ideas back and forth, i mean, you're looking at -- at dave watson for this thing. >> absolutely. >> this is a guy who kills when the issue of his child custody is challenged. >> those similarities became glaring. >> but it doesn't seem to go anywhere investigatively. >> it does not. there is a lack of physical evidence in this case. and the suspect has an alibi for both nights. >> reporter: three women gone and no answers on the desert horizon. >> and now all three investigations are in the vault. >> all three go cold. >> reporter: coming up. for some people cases never go cold. >> i just couldn't believe that these innocent women were murdered and no one was talking about it. apparently, somebody was. >> i just found out they're investigating me again. pressure. i feel it everyday. but at night, it's the last thing on my mind. for 10 years my tempur-pedic has adapted to my weight and shape, relieving pressure points from head to toe. so i sleep deeply and wake up ready to perform. ♪ now through june 11th, save $600 when you buy select tempur-pedic adjustable mattress sets. find your exclusive retailer at tempurpedic.com. sorry about the holdup, folks. we have some congestion on the runway and i'm being told it'll be another 15, maybe 20 minutes, and we will have you on your way. ♪ runway models on the runway? surprising. what's not surprising? how much money evan saved by switching to geico. i would not wear that lace. hmm, i don't know? fifteen minutes could save you fifteen percent or more. >> reporter: by the spring of 2003, three women in dave watson's orbit were either missing or dead. detectives had their suspicions, but no hard evidence dave had committed any crime. and so the cases of linda, marilyn, and renee sat quietly, collecting dust in the cold case vault of the sheriff's department. >> we keep waiting and -- and listening and hoping that -- that something will come up. they'll find something that proves that dave did this. >> reporter: and all the while, dave continued to climb the ranks at the tucson fire department, even if he couldn't quite shake the shroud of suspicion that surrounded him. >> i mean, this is -- tongues are -- tongues are wagging in tucson, right? >> oh, absolutely. >> reporter: matt mcdonald, cortney corcoran, and richard johnson all rode horses with dave and worked with him at tucson fire department. >> i mean, i -- i went into a station and -- where dave was working, and the phone rang. and one of the guys picked up the phone, and they go, "hey, killer. phone's for you." >> yeah. >> you guys -- >> i mean, it -- >> you guys are tough. >> somebody called him cold case, is that true? >> i did. >> yeah, he -- i think, yeah. >> you did, matt? >> i did. [ chuckles ] >> reporter: one day, his friend matt decided to ask dave point blank if he had anything to do with the murders. >> he was very candid with me, and we spoke for probably four hours that morning. >> you had questions, matt. did he answer them for you? >> he did answer them. >> reporter: his buddies were convinced, dave had done nothing wrong. >> i never had any doubt that he was innocent. >> you don't see him as -- guy in the hoodie with the nine millimeter. >> no, i do -- no -- no, i do not. not at all. >> i -- i never called him on it because i never suspected dave. >> reporter: despite the whispers around town, dave never left, and jordynn says he remained focused on his kids. >> my dad really tried to make everything normal. so, you know, we could have a normal childhood. >> reporter: but the ongoing investigation took its toll on dave and rosemary's marriage. >> i said, "i can't do this anymore." and he said, "okay." he asked if there was anything that he could do, and i said, "i don't think so." >> reporter: by 2007, they'd divorced and moved on. >> mega 1063 tucson's old school and r&b. good morning everybody. this is rosemary. >> reporter: rosemary worked as a radio disc jockey, supporting her family, including her adoptive daughter, jordynn, who lived primarily with her. dave was promoted to fire department captain. >> he earned it. it was not given to him. he earned it. >> reporter: time, as it tends to do, kept moving on. but here in the cold case vault sat those three cases, linda, who was officially declared dead in 2006. marilyn, and renee. >> i think my biggest concern was always them being forgotten. >> reporter: linda's friend, marnel, did what she could to keep that from happening. >> for years, i sent letters to all the media, you know, just saying, "here's the story." i was always just shocked that there wasn't outrage in the community. i just couldn't believe that these innocent women were murdered, and no one was talking about it. >> reporter: but by december, 2007, it seemed as though there'd been a huge break in the case. the local papers reported that the sheriff's department had new evidence. "information in the case is snowballing, and we have to pursue that," said an investigator. in reality, it was all a bluff. the cops planting a story, hoping to pressure dave. they tapped his phone, too, and recorded this call he made to rosemary. >> i just found out they're investigating me again. >> that what? >> have the detectives come and talked to you yet? >> no. >> i just wanted to let you know, because i just found out. if they decide to knock on your door, or come to the radio station, tell them to f off. >> reporter: dave seemed to suspect someone close to him was talking to the cops. >> when i got into his truck, he asked me if i was wired, and he felt me out. >> reporter: detectives interviewed a friend of dave's named luis who told investigators about something dave said at a party one night. >> he said, "i know where she's at." period. >> and when he said, "she," did he say, "i know where linda's at," or, "i know where she's at"? >> well, obviously, the conversation was about linda, i think. >> it was about her. >> reporter: not so, said dave's best friend's wife, who was at the same party. she said dave was talking about a missing dog, not linda. hard to tell if it was just an innocent misunderstanding or a slip of dave's tongue that indicated something sinister. the mystery of linda's disappearance and marilyn and renee's murders, no closer to being solved. no way of knowing that out there, in the desert, an answer had already been found. coming up. someone took a horse ride out to the middle of nowhere. what was he looking for? >> it seems very coincidental that you would ride it there. when at that point in time nobody else knew. when "dateline" continues. ♪ only tylenol® rapid release gels have laser drilled holes. they release medicine fast, for fast pain relief. tylenol® (cat meows) ♪ (snap) ♪ (cat meows) sheba® perfect portions™. what cats want™ internet speeds 20x faster. at&t fiber sounds amazing. wait a sec, i'm not done yet. less than 12% of at&t homes actually qualify. huh... hold on. everyone else gets our other, slower internet speeds. but no one reads this stuff anyway. except for the old guy with the binoculars. huh... we got ourselves a reader. don't be fooled by at&t. xfinity delivers the fastest speeds to the most homes. president trump expected to lamd in saudi arabia withing the next 90 minutes. this begins his first foreign visitas presdient... 5 countries in 9 days. we )re tweeting updates. =add= and be careful of that weekend barbeque. more than 100 tons of nathan )s hot dogs are being recalled nationwide, because of possible metal fragments. we )ve posted the details on our homepage. we )ll see you at 11. >> reporter: linda watson had been declared legally dead. but no body had ever been found. so there was no proof of a crime. and no case to make against her ex-husband, dave watson. not for linda's disappearance. or for the subsequent murder of her mother and a friend. all that changed because of a random discovery. and a long-delayed lab result. >> where -- where are we, detective? why here? >> we are outside the silver bell mine area that being the silver bell mine. >> yeah. >> very remote area, the northwest side of tucson and pima county. >> reporter: remember j.r. had lived off of silverbell road. silverbell mine was near the same road, but 20 miles from where j.r. lived. way back in october of 2003, not long after marilyn and renee were killed, hunters found a partial human skull here. >> this is a high trafficked area for undocumented border crossers. and unfortunately, many in the summertime, in the hot summers of arizona, do not make it and perish in this area. >> reporter: the medical examiner's office in tucson runs a unique program to identify such remains. but it takes time. so a small portion of the cranium was removed for dna testing at a later date. much later. >> eight years later in february of 2011 we finally get a dna match back from that skull that was found in 2003, and it is a positive match for linda watson. >> reporter: suddenly the skull was a big priority. there was no sign of trauma, no evidence of how she'd died. still, eleven years after linda watson disappeared, at last, here was proof she was no longer alive. >> that's when you have a case. >> that's when i have a case. >> reporter: indeed, he did have a case. three of them in fact. detective anderson took over as lead detective after linda's skull was identified. >> by the time i got the case in 2011 -- it was 11 years old. and there was 11 years of investigative work that had been done. and i had to start piecing it together. >> reporter: it took him a year just to read through it all. there were so many things that stood out. but one in particular caught his eye. it happened years before linda's remains were identified. >> it was an aha moment for me. >> reporter: back in 2007, when detectives planted that news story about the case heating up, they also put a g-p-s tracker on dave's vehicle. >> i discovered gps coordinates that indicated on december 31st, 2007 he drove his truck and his horse trailer and rode a horse within hundreds of yards at least -- no further than 1.1 mile of where linda watson's skull was found back in 2003. >> speculate. what do you think was going on? >> i think he was going back to the scene to see if he saw anything, if we were there, if we'd been pokin' around, if nothing had changed. it seems very coincidental that you would ride it there when at that point in time, nobody else knew that linda watson was out there. >> reporter: after studying every detail of the case. detective anderson found it convincing. >> it was obvious to me and everybody i presented this case to that only one person committed these three murders and that one person was david watson. >> reporter: and he had a theory about how linda's murder went down at her house. >> manner of death, do you see it? >> i have no idea. something that creates a great amount of blood. and i think that he takes linda in the very early morning hours out towards the silverbell mine and buries her in a shallow grave in the wash. >> reporter: and as far as detective anderson was concerned, dave was the only person who had motive to kill marilyn too. >> motive outweighed everything in this case. we have two women who took him to court over his daughter. he got what he wanted as a result of these homicides. >> enough to go forward? maybe. but this wasn't the only high profile cold case being rescued from the vault at the time. dateline covered the case of gary triano, who was killed when his car exploded in the parking lot of an upscale tucson country club in 1996. >> they had new leads on that one, things to follow and do right now. >> reporter: another four years passed. that other case was solved. and then in 2015 -- >> bam, bam, bam on my front door, thought the thing was gonna go break in. and there's cops out there in tactical wear. they asked me to step out. four guys threw me to my gravel driveway. and i said, "i think you guys got the wrong person." >> i told him that, "you're under the arrest for the murders of linda watson, marilyn cox and renee farnsworth." >> and i like -- "you're-- no. i told you before i didn't do any of this." >> you know and i told them, "i-- i didn't do this stuff." you know, "i'm innocent. i told ya." >> reporter: linda watson's friend marnel saw the news on tv. >> "we arrested david dwayne watson on three counts of first degree murder." >> all of a sudden, i just couldn't breathe and i said, "oh my god, this is it." and i just -- i started tryin' to call her aunt -- pat and she just said, "this is it." and i was, like, "are you sure? are you sure?" ( laugh ) i just remember screaming and crying. and -- and she said, "they just arrested him." >> i couldn't believe it. i just couldn't believe it. >> this is 15 years -- >> yeah. >> -- after linda's gone missing. >> yeah. i just could not -- and i still have to pinch myself. >> reporter: dave's daughter jordynn couldn't believe this day had come, either. but for a very different reason. she fully supported her father. believed there was no way he killed three women. >> all they really had was, you know, that he was in a custody battle. and it seemed like a vicious custody battle. >> and when it came to a climax -- >> uh-huh. >> -- somebody died? >> yes. and that's all they had. there's no hard evidence putting him somewhere, you know. no murder weapon in his hand, nothing like that. they never found anything. you know, his dna isn't anywhere that they were. >> reporter: and remember, dave had a solid alibi. his wife at the time, rosemary, told detectives she was with him, at home, when all three women were killed. he pleaded not guilty, and in a recorded call from jail, told his friend mike bratton he was counting on his daughter and his ex-wife to defend him. >> i want jordynn to be a witness on my behalf and -- and i need rosemary, i really need rosemary to be my witness, too. um, otherwise, um, it's -- it's --. you know, i -- we were a team once, we need to be a team again. >> reporter: dave had a big surprise coming. did he ever. >> coming up, rosemary's dark and dangerous secret. >> how do i look my daughter in the eye and live the rest of my life knowing what i know? my daughter is... ...studying to be a dentist and she gave me advice. she said dad... ... go pro with crest pro-health. 4 out of 5 dentists confirm these crest pro-health products... &help maintain a professional clean. crest pro-health... ...really brought my mouth... ...to the next level. go pro with crest pro-health is thno, it's, uh, breyers gelato indulgences. you really wouldn't like it. it's got caramel and crunchy stuff. i like caramel and crunchy stuff. breyers gelato indulgences. it's way beyond ice cream. rumor confirmed. they're playing. -what? -we gotta go. -where? -san francisco. -when? -friday. we gotta go. [ tires screech ] any airline. any hotel. any time. go where you want, when you want with no blackout dates. [ muffled music coming from club. "blue monday" by new order. cheers. ] [ music and cheers get louder ] the travel rewards credit card from bank of america. it's travel, better connected. the travel rewards credit card from bank of america. we, the entertainment-loving people, want all our rooms to be tv rooms. because those are the best rooms. because they have tvs in them. and, when we're not in those rooms, we want our shows to go with us. anywhere? you got that right, kid show thing. get a directv all-included package for 4 rooms. only $25 a month, price guaranteed for 2 years. available for at&t unlimited plus customers. >> reporter: for seven years, rosemary watson carried the knowledge buried down deep. it festered. ate away at her. >> if i never said a word to anybody, you know, how do i look my daughter in the eye -- you know, and live the rest of my life knowing what i know and keeping that. >> reporter: rosemary said the seeds of this dark secret first took root in august 2000. the night linda disappeared. she, of course, had been her husband's alibi. told investigators he was home with her all night. but, she told us, that wasn't entirely true. in the middle of the night, she said, she actually woke up. >> and dave wasn't in bed. and i got up. and i -- i kinda walked through the house. and i didn't see him. and i went and i laid back down. i fell back asleep. >> reporter: some time later, she said, she woke up again. and he was not in bed with me again. and i was looking for him, and through the house, kinda peekin' out into the backyard. and then, i saw him. >> where was he? >> he was standing at the back of his jeep. i could see him through our -- our kitchen window. >> he appeared to be -- he looked as though he was, you know, just kinda cleaning out the back of his jeep. >> and then, he comes in? >> he does come in. and he said, "i went for a walk." and i asked him if he was okay. and he said yeah, he just needed to clear his head. >> that make sense to you? >> it -- it did make sense to me. i had no reason to doubt him at all, none. >> reporter: and then, rosemary said, dave handed her something. >> he actually handed me a box of latex gloves, you know, and said, "put these away," which, you know, i didn't think anything of it at the moment. >> this is your new husband you're in love with? >> absolutely. >> you don't know all his habits? >> nope, still learning. >> he might get up and talk to the birds-- >> he -- >> you don't know. right? >> he was an early riser. >> reporter: and so when investigators showed up, and asked where dave had been the night linda disappeared -- >> i didn't mean to lie. that wasn't my intent, was to lie to law enforcement. >> did you say, "dave's in a jam here. i gotta cover for him"? >> i said, "i love my husband. he went for a walk. it looks really bad and very suspicious that he went for a walk. now, suddenly all this is happening, you know. he said, "i'm home." and i'm like, he's home. >> reporter: so no walk, he was home all night. that was her story. and she stuck with it. although privately, she said, she couldn't help but turn things over in her mind. and at one point even confronted her husband. >> what i said was, "please tell me that you're not involved, that noth -- you know, this has nothing to do with you." >> what'd he say? >> "i didn't do anything." >> and that was enough for me. and i said, "okay." >> reporter: and so three years passed. rosemary gave birth to her son, adopted jordynn, and battled over visitation rights with marilyn. and then on may 8th 2003, the investigators were at the door again. marilyn and renee had been shot. where, they asked, had dave been around 8:30 that night? dave and rosemary, as we know, said he'd been at home. but, the truth? >> at that moment, rosemary, was dave home? >> dave was not home. >> reporter: according to rosemary, dave did not get home until after jordynn was already tucked into bed, sometime after 9pm. >> and he walked in. and i saw his face. and it's something that nobody will ever, ever take away from me. >> tell me. >> panicked, which panicked me. white as a ghost, sweating, i mean, just -- his eyes were huge. and it just instantly -- it scared me, the very first thing i said was, "what's wrong?" and he didn't say anything. and i said dave, what is wrong? and he didn't say anything and and he leaned down, kissed jordynn. and he shut off the light. and he kinda pulled me around the corner. and i kept asking him, "what is wrong? what's going on?" there were a lot of, "what the hell is happening?" >> he started to take off his clothes in the kitchen, and quickly. and he said, "wash those. i'm getting in the shower." and he made a beeline for the shower. >> reporter: and then, when the investigators showed up at the door -- >> he clearly stated, you know, "been home." >> they asked you directly, "was dave here?" >> yes. >> you told 'em a lie? >> i absolutely did. i followed dave's lead >> reporter: but rosemary says her insides churned. >> i mean, it really took a toll on me physically and mentally >> just everything terrified me. dave terrified me. >> he handed me knowledge that i didn't wanna know. i didn't ask for it. i didn't want it. and he left me there holdin' it. and it became a very, very heavy burden. >> is that when your marriage c -- becomes unraveled with dave, would -- >> it definitely starts there. it never was the same after that. it never was the same. >> reporter: the dominoes, said rosemary, quickly began to fall. dave's behavior changed, and he had an affair. months after marilyn's murder, rosemary confronted him again. >> i said, "i think you killed three women." and his response to me was, "are you afraid of me?" >> reporter: dave, she said, blamed her for the suspicion that had fallen upon him. >> he had made statements, you know, saying, "people are saying that you're telling this town that i did it." and what he told me is, "you need to shut your mouth." and what i said was, "i'm your -- alibi." and that was a quote. and it -- and it was kinda left at that. >> reporter: a few years later, rosemary and dave were divorced. and it was in the midst of an argument over child care arrangements that rosemary said everything came to the surface. >> the moment that hit me, was just when i said, "please don't make me take you back to court." and when i said that, he took off his sunglasses and he said, "don't -- with me, rosemary." >> and it did. it scared me. >> did you fear for your life at that point? >> i -- >> linda, marilyn, renee. "i might be next here. i might be the subject of this, whatever -- going on with this guy." >> there is a moment, yes, that i did. >> reporter: after this confrontation, rosemary confided in her best friend, who urged her to call the sheriff's department. she met with an investigator. >> and i told him straight out. i said, "i lied both times." and i think as we went through conversation, you know, it kind of ended with, "i never believed you anyway." [ laughs ] >> but the alibi had gone up in smoke? >> yes. and there was no turnin' back. it was -- it was the truth. >> reporter: detectives kept rosemary's confession secret as they slowly built their case against dave. when he went on trial, she would be the star witness. but, by her own admission, rosemary had lied for years. why would a jury believe her now? >> coming up -- >> did any of that get to you, jordynn? did she plant a seed? >> no, knowing my father, i really don't feel he could go as far as to kill a woman. >> a daughter defends her father. and, explains herself. >> being a 7-year old, i probably wasn't very clear. >> when dateline continues. for d non-small cell lung cancer, previously treated with platinum-based chemotherapy, including those with an abnormal alk or egfr gene who've tried an fda-approved targeted therapy... this is big. a chance to live longer with opdivo (nivolumab). opdivo demonstrated longer life and is the most prescribed immunotherapy for these patients. opdivo significantly increased the chance of living longer versus chemotherapy. opdivo works with your immune system. opdivo can cause your immune system to attack normal organs and tissues in your body and affect how they work. this may happen any time during or after treatment has ended, and may become serious and lead to death. see your doctor right away if you experience new or worsening cough; chest pain; shortness of breath; diarrhea; severe stomach pain or tenderness; severe nausea or vomiting; extreme fatigue; constipation; excessive thirst or urine; swollen ankles; loss of appetite; rash; itching; headache; confusion; hallucinations; muscle or joint pain; flushing; fever; or weakness... as this may keep these problems from becoming more serious. these are not all the possible side effects of opdivo. tell your doctor about all your medical conditions, including immune system problems, or if you've had an organ transplant, or lung, breathing, or liver problems. a chance to live longer. ask your doctor about opdivo. see opdivotv.com for this and other indications. bristol-myers squibb thanks the patients, nurses, and physicians involved in opdivo clinical trials. anyone can get you ready, holiday inn express gets you the readiest. because ready gives a pep talk. showtime! but the readiest gives a pep rally. i cleared my inbox! holiday inn express, be the readiest. hthat's why new downyl can saprotect and refresh conditions fibers to lock out odors. so clothing odors don't do the talking for you. lock out odors with new downy protect and refresh. a 10-speed direct-shift 5.0transmission.ine. a meticulously crafted interior. all of these are feats of engineering. combining them with near-perfect weight distribution... ...is a feat of amazing. experience the first-ever 471-horsepower lexus lc 500 or the multistage hybrid lc 500h. experience amazing. >> reporter: pima county prosecutor jonathan mosher spends his weekends about as far from a courtroom as one can get. >> i need a way to get it outta my head. rock climbing, you have to be completely focused in the moment, not worried about you, yourself, your life or anything. >> all the chatter in your head stops? >> and it's liberating. it just scratches an itch that i need to be able to go back and do the next case. >> reporter: and there were few cases as daunting as the one he took on in 2014. >> the defendant, tucson fire captain david watson, accused of killing three women. >> this is the pinnacle for a prosecutor. to take the challenge, make the challenge almost insurmountable, make it big and overcome it. >> reporter: mosher and his co-counsel, nicol green, felt they were up to the challenge. >> we had no doubt, no doubt that david watson killed these three women. we just wanted a chance to put it in front of a jury. >> we will start with the state. >> reporter: that chance came in october 2016. >> two women battled david dwayne watson for control and custody of jordynn watson, two women who are both dead. >> reporter: the prosecution called jordynn, who still believed her dad was innocent, to testify about that interview she gave at age seven. >> i said, "is dad still at his meeting?" she says, "i don't know." >> that is number one corroboration for when rosemary comes forward later and says that david watson was not home. >> being a seven-year-old i probably wasn't very clear, of course. [ laughter ] but, yeah, i have no memory of that at all. >> reporter: and, she told us, her relationship with rosemary was never the same after rosemary started expressing doubts about dave. >> did any of that get to you, jordynn? did you start to turn these ideas around in your head? did she plant a seed? well, is there something to this? >> she really tried. [ laughter ] i'll give her that. but no, knowing my father, i really don't feel could go as far as to kill a woman. >> reporter: don't let the helpful, fire captain image fool you, said the prosecution. dave's training, they said, is exactly why he was capable of killing three women. >> so on one day you may see him saving someone of a heart attack in his emt van. but on other days, there's a different side to him, huh? >> but what does a paramedic do? responds to bloody scenes. they remain calm in such circumstances. and this was david watson's key attribute. >> reporter: that, along with a mountain of other circumstantial evidence. the money clip, the 9mm shell casings, dave's statements to his friends, the horse ride near silverbell mine in 2007, all pointed to a guilty man, according to the state. >> you prove this case by a thousand cuts, a thousand little cuts. and there's not going to be the one aha moment that comes down from on high and solves this case. >> reporter: wrong, said the defense. there wasn't an aha moment because dave didn't do it. representing dave watson. partners in law, and marriage, nastasha wrae and michael storie. and much like their prosecution counterparts, not ones to shy away from a challenge. >> this is the most monstrous undertaking we've ever had in our careers together. >> reporter: according to the defense, there were any number of reasons why linda, renee, and marilyn died. reasons that had nothing to do with dave watson. >> as much as the state says, "dave watson, dave watson, dave watson," you're going to see it going in other avenues of people and circumstance. >> reporter: other avenues, such as suicide. whether linda's -- >> with the drinking and the ex-boyfriend testifying against her, losing her job. >> reporter: or even renee's. the defense said marilyn's friend had once discussed suicide. and they suggested she may have chosen an unusual method. >> we all know insurance won't pay if you commit suicide. >> your theory or at least you're willing to consider it that renee, the friend, has somehow commissioned her own murder? >> that was something that we had thrown out. >> mean, natasha, really. >> what movie are you seeing? >> there's some crazy people out there. >> reporter: then there was the idea that maybe linda's ex-boyfriend j.r. was the culprit here. dna consistent with j.r. and not dave, was found on a trash bag that had linda's blood on it. although j.r. himself testified, nothing surprising about that. he said he'd been helping linda fix up her house, and that he had nothing to hide. >> have cooperated with the sheriff's department in their investigation 110%. >> and remember how linda went out drinking with her cousin a few days before she disappeared? the circle s saloon isn't far from a rural part of town called "green acres" a witness testified she had heard someone in green acres talking about moving linda watson's body. >> she reports that that body was being moved to silver bell road. and that is within four miles of where the skull was found. >> the geography matches. >> she had it. >> and this would fit the theory that linda got into the wrong pickup truck. >> right. >> reporter: the defense said dave, an avid rider, had ridden out near the silverbell mine before but as for that specific trip on new years eve 2007. >> i don't think that happens. >> you don't believe he went for the ride? > uh-uh. >> reporter: the defense highlighted that while pima county sheriff's investigators provided a print out of the gps coordinates, they never saved the raw data. and what about that money clip with the initials "ddw?" the defense theorized, maybe marilyn's family planted it. >> we have our theories that this family was looking for a scapegoat and they believe dave did it and so they planted the money clip. >> reporter: ludicrous, said marilyn's sisters. >> we may be old, but we ain't senile. >> and if i -- if i was gonna do something that stupid, i -- i would took it up front where the crime scene was. >> why would i put it clear in the back? >> reporter: the defense also pointed out that there was no provable link between the ruger dave once owned and the gun that killed marilyn and renee. >> it's not conclusive that it was a ruger. >> reporter: but at the end of the day both prosecution and defense agreed. this case hinged on the believability of one witness, rosemary watson. >> if you do not believe rosemary, we don't have a case. >> reporter: rosemary explained to the jury why she decided to come forward in 2007. >> i knew that i could not hold this in an -- any longer because three women lost their lives. and their lives mattered. >> reporter: and then there was a critical detail. rosemary testified that on the same day linda disappeared, dave found out his own mother was planning to testify on linda's behalf at the upcoming custody hearing. >> he begged her not to. >> did he succeed? >> no. she was very adamant about testifying for linda. >> reporter: the prosecution said everything was coming to a head that night. >> it's about control. and that's a man who's seething inside the night that he finds out he can't get his mother not to testify against him, his own mother. and that's how vicious it had become. >> so you see the fuse being lit here. >> i don't know when the fuse was lit. but it was getting down close to the explosives at that night. >> reporter: but according to the defense, rosemary watson was just not credible. >> she's either lying back when she gave the alibis or she's lying when she recants the alibis. >> pick it. they -- >> well, they shouldn't pick it. they should take it and say, "i can't believe anything she says because i don't know what to believe." >> so for a seven-year span you have this story you're calling a lie now, right? >> it is a lie. >> and then the last seven years is the truth, right? >> i came forward and told the truth. >> i understand. they're completely different versions of those nights, yes? >> they are. >> one of them is a complete lie, yes? >> correct. >> that's all i have. >> reporter: the defense, in a nutshell, hell hath no fury like a woman scorned. >> so she's lying to stick it to her ex? that's -- that's your theory? >> exactly right. >> reporter: a point the defense drove home in closing arguments. >> she's a liar. and when you have a blatant, bald-faced liar like that you cannot consider their testimony. you have to throw it out -- >> reporter: the prosecution argued the jury should believe rosemary. and not the wild theories floated by the defense. >> the truth is, folks, in august of 2000 that man killed linda watson. in 2003 that man killed marilyn cox, and killed renee farnsworth. there is no other evidence based in reason to any other answer than that. >> reporter: and now it was in the hands of 12 jurors. and right before thanksgiving. they'd surprise everyone. >> coming up. after so many years and one last twist, a verdict. >> we were all pretty positive that, you know, this is gonna be over, he's gonna come home. >> my hands were sweating. i was nervous because i know the victim's families are behind me. and this is everything to them. to sprint. well, their network reliability is within 1% of the big guys. and they have the best price for unlimited among national carriers and... wait! are you watching this on the awesome iphone 7? you gotta get iphone 7 from sprint! the screen is incredible! and the only thing better than iphone 7... is iphone 7 on sprint. who's he talking to? i don't know, but i better go to sprint. wait! 2 iphone 7s! love you! get sprint unlimited. and now get iphone 7 on us! for people with hearing loss, visit sprintrelay.com let's think about what goes in hoh., renee. and we think ba-blam's gonna kill the stomach flu? i'm scared to use the facilities. i don't blame you. if you want clean, your cleaner needs bleach in it. clorox means clean. does your makeup remover every kiss-proof,ff? cry-proof, stay-proof look? neutrogena® makeup remover does. it erases 99% of your most stubborn makeup with one towelette. need any more proof than that? neutrogena. ♪ whether you dry, curl or straighten you can visibly repair 7 types of damage with tresemmés new repair and protect 7 with biotin tresemmé puts in the work so you can work it everyday, millions of you walk through our front doors. and you inspired our new flavors. introducing mcdonald's signature crafted recipes. sweet barbecue bacon made with crispy onions. pico guacamole made with real hass avocados. maple bacon dijon with thick-cut applewood smoked bacon. purchase any signature crafted recipe sandwich and use the mcdonald's app to get a free medium fries and soft drink. you bring your flavor to the world... we bring ours to you. >> reporter: jordynn watson firmly believed her father was innocent. and expected to have him home for thanksgiving. >> you know, we were all pretty positive that, you know, this is gonna be over, he's gonna come home. >> reporter: then, three days after deliberations began, the jury came back. but it wasn't what anyone expected... >> was there any possibility that the jury would want to consider further discussions. >> not at this time, no. no sir. >> reporter: the jury was hung. dave watson soon learned he'd been just a few votes shy of walking out of jail a free man. >> it was ten to two acquittal in the case of linda, and eight to four for acquittal in the case of marilyn and renee. >> yeah, it brought tears to my eyes that it was even a hung jury. >> reporter: the defense contained their excitement, and braced themselves. >> anything short of a conviction is a win. but it's a hollow win in that the state can come right back and charge it again. >> reporter: which is exactly what happened. the retrial began on january 25th, 2017. the prosecution led with its star witness. >> state calls rosemary watson. >> reporter: but this time, they retooled their case a bit. >> i read the transcripts from the first trial. and one thing i saw too much of was me speaking. and so i doubled down on the idea that the jury needed to hear from rosemary. and so i got out of the way. i asked shorter questions. >> did anything unusual happen that night? >> yes, i woke up a couple of times in the middle of the night and dave was not there. >> reporter: the second time around was different for rosemary too. >> now i'm a little mad. not only is he lying, he's making me out to be just a bold-faced liar. >> reporter: she testified about how she had lied to protect her family and about what coming forward with the truth had cost her. >> does jordynn call you mom anymore. >> jordynn doesn't speak to me very often anymore. >> is that since this case? >> correct. >> reporter: the prosecution called jordynn next, so the jury could hear how her interview, at age seven, backed up rosemary's claim that dave wasn't home. not so fast, said the defense. >> i can only imagine if my seven-year-old was interviewed about a key fact that's gonna decide a guy's life. it would be scary. >> reporter: the defense maintained dave was home the nights in question. he didn't kill anyone, they said. they once again presented multiple other scenarios of what could have happened to linda. she committed suicide. she was murdered by a mysterious killer from green acres. or by the one suspect who stood out for the defense. >> if not dave watson, then who? >> it would be carl. >> reporter: carl barton junior, j.r. nonsense, said the prosecution. >> there is no evidence linking j.r. to any of these three murders. none. >> reporter: after seven weeks of testimony, dave's fate was once again in the hands of a jury. >> we were getting indications from questions out of the jury that they might actually go into the next week. i was thinking, "they're pretty hung." >> reporter: but then, after a day and half of deliberations, the jury buzzed with a verdict. it was st. patrick's day. detective kelly anderson hoped luck would be on his side. >> my hands were sweating. i was nervous. i'm nervous over every verdict. but i'm more nervous now and it's because i know the victims' families are behind me. and this is everything to them. >> reporter: the stakes were high for him personally too. he was retiring, and this was his last homicide case. the moment of truth, the one that had taken 17 years to arrive was finally upon them. >> we the jury do find the defendant david duane watson guilty of second degree murder of linda watson. >> oh. when he said linda, i didn't even have to listen to the rest of it 'cause we knew if we got him for linda, the other two was just an automatic. >> slam dunk. yeah. >> reporter: david watson, father, friend and fire captain was also convicted for the first degree murders of marilyn and renee, the loyal friend who didn't even play a lead role in her own murder case. >> she was forgotten a lot but my mom was the meek quiet person in the back went with the flow, she was always there for anybody that needed anything. >> reporter: jordynn was heartbroken. dave says he could not believe it. >> i would have never imagined that in a million years. from what was being presented in court i've thought, "there's no way -- no way beyond a reasonable doubt you could think i would have done any of this." >> did you go over to linda's house, abduct her, kill her? >> no. >> drop her in the wash up by the silverbell? >> no. not at all. >> did you get a 9mm, your ruger -- did you put on a hoodie and go kill marilyn and her friend in the driveway of their house? >> sure did not. >> point-blank range. >> nope. >> who do you think did? what's -- >> skip it. >> what's your theory? >> no. we can't do that. sorry. >> reporter: his attorneys would not let him answer that question, citing dave's pending appeal. the man who made a career out of saving lives, is now doing time for taking them. dave watson was sentenced to life in prison. >> is it a kind of nice sentimental ending for your career as a homicide detective? >> it's kind of bittersweet. there's a little bit that makes me wanna do it again. >> reporter: the vault is three cases lighter now. and the families of linda, marilyn and renee have some measure of closure thanks to an enemy-turned-ally. >> one of the ironies here is that -- you ended up delivering for women that you had been fighting earlier in your life. you delivered for linda, you delivered for marilyn and her friend renee. >> ultimately i did, didn't i? >> reporter: she hopes jordynn will one day come to understand. >> speak to her directly now. >> everything that i didn't want for her has happened. and so speaking to her, i guess the only thing i can say is that i'm sorry. but i am always here for her. >> you're sorry but you say you also did the right thing? >> i did do the right thing. if this was me and i died fighting, you know, for justice for my daughter, i would hope that everybody would just tell the truth. >> reporter: but the truth: sometimes as murky and hard to see as the desert with night closing in. what with all those secrets and old bones scattered about. unchanging. >> that's all for this edition of dateline. we'll see you again this sunday at seven, six central and then again next friday at nine, eight central. i'm lester holt. for all of us at nbc news, goodnight. next at 11, the amber alert is over. we have new video that shows the rescue of a bay area toddler hundreds of miles away. and today we investigate a website matching people with unlicensed contractors. >> he ripped me off. >> next. that statewide amber alert... deactivated. the ch right now at 11:00, the statewide am bert alert has been deactivated. the search is over for a little boy from the bay area. you can see him here. he's a long way from home. the news at 11:00 starts right now. good evening, thanks for being with us i'm raj matthai. >> i'm jessica aguirre. the big clue tonight, the pinning of a cell phone. we have been tracking this story all evening. the 21 month old baby boy safe.