enter this guy. >> he sees things other cops don't see? >> phenomenal. >> they call him the evidence nc whisperer. he's about to crack this case open before your eyes. >> the answer was in the details? >> it was right there. >> and you won't believe how. >> you walk out of there thinking i spooked him, it worked? >> i hoped. i wasn't quite sure. >> hello, and welcome to "dateline." 20-year-old lynsie ecland and her mother nancy told each other everything. or so her mother believed. when the college student vanished after a night out clubbing, nancy thought she was at a sleepover with friends. and that wasn't the only secret lynsie was hiding. it would take years for detectives to uncover the truth buried in a pile of lies. but could they find lynsie? here's josh mankowicz with "the night lynsie disappeared." sometimes the facts are as clear as the southern california sky, but other times you have to know where to look to see the truth.u this man has made a career of noticing what others do not. >> what's his reputation? >> meticulous investigator. just pores over the volumes of evidence and finds things that other investigators did not find. fi >> the evidence whisperer? >> correct. >> that night i went out -- >> does this man act guilty? does he know more than he's saying? m >> well, i didn't know anything was going on, all right? i was just like, where's lynsie? okay? >> what about this man? can you believe the story he's telling? >> i was supposed to pick her up twice and she was so out of character. she didn't show up on either day. >> the evidence whisperer wasn't present at either of those it interviews, but watching them helped him solve the mystery of what happened to a vivacious young woman and bring answers to the mother who loved her. mo >> i was always proud of her. she was a real fighter. >> lynsie ekelund arrived on july 22nd, 1980. she was the youngest of three. maybe that fighting spirit isn't visible in her photos, but her mother nancy said it was always there. lynsie had a passion for animals. she helped out in her spare times at a local shelter. kim davidson, who worked at lynsie's middle school, remembers young lynsie also had a sense of compassion. >> i was freezing cold and i didn't bring a jacket that day.b i felt these little hands up on my shoulder and a sweater come up around me and i turned around and it was lynsie and she said i just can't stand sitting here seeing you shiver.g >> lynsie gave back in other ways.u her mother said lynsie would lie about w her age so she could giu blood. remarkable because lynsie struggled with her own disabilities. her left lung was paralyzed.le b her left leg impaired.mp >> did she ever talk about how she had become disabled? >> she had brought it up to me. she said she was in a car accident and thrown when she was a little girl but very, very t just like matter of fact. >> but growing up lynsie needed so much care, her mother nancy was with lynsie like her shadowi >> she was my only purpose in my life is to make her as normal as she could be. >> by the time kim met lynsie, lynsie's dad and brothers had moved away. kim remembers a very tight family unit of just two. >> how close were lynsie and e nancy? >> unbelievably. extremely. >> but as lynsie reached adolescence, that started changing. like a lot of teens she wanted her own identity.ce she changed the spelling of her name from this to this. by high school there were girlfriends, even some boyfriends, and by the time she was 20 after so many years of mom and daughter being each other's best friends and confidantes, lynsie began to keep some things in her life to herself. like where she was really headed one night in february 2001.he >> does it make any sense that she would lie to you about what she was going to do that night? >> i've never known her to lie to me but you don't know what you don't know. >> it was a friday night. lynsie was in college part-time and working but still living at home. she told her mom that instead of their usual friday night dinner she was staying the night with a girlfriend named andrea, someone nancy had never met.nd and then a young man named chris came to the door to pick lynsie up. >> she introduces you to this guy chris. did chris say hello to you? >> uh-huh. >> was he polite? did he have good manners? >> uh-huh. >> but nancy says something felt wrong. >> i had a feeling about him. >> what feeling? >> i don't know. >> but you put it aside? >> uh-huh. >> of course, nancy was used to things feeling wrong. she had spent so many years worrying about lynsie. it was a struggle to let go, but she did. >> the last thing i said to her was remember your seat belt, and she looks over her shoulder and she says, "back at you, mom. love you." that's the last thing she said to me. >> nancy locked up the house ans went to bed. the next day lynsie was supposed to call after she was done tutoring two girls from the tee neighborhood, but when the call never came, nancy drove over and found out lynsie never showed ur at her job. >> all of a sudden my daughter is not where she's supposed to be. she had taught these little girls like for four months about. >> and you have no way of htgi reaching her? >> i had no way. >> nancy ekelund was frantic. >> i started calling hospitals. i called the morgue. that's how desperate i was. see if there was a jane doe in the morgue. >> there was no jane doe. and there was no lynsie ekelund. most people who disappear like that, they come back in a couple of days. >> if not 24 hours, yes. >> is that what you thought was going to happen? >> i think we did. f >> corrine loomis was a detective with the police department. >> we had no unidentified bodies? >> you checked the e.r.? >> we checked everybody, we checked everybody, we checked everything. there was no sign.bo it was as if she vanished. >> coming up -- >> when was the last time you saw lynsie? >> a week ago now. >> when "dateline" continues. there are thoughts that are hard to control you're not good enough but i am enough music and i know what i'm made of put your skin in the game with a razor that puts your skin first venus my skin. my way. did you know you can shorten your cold [♪] with cold-eeze® lozenges. cold-eeze® can shorten your cold by 42%. it releases zinc ions that some scientists believe inhibit cold viruses from replicating. try cold-eeze® the number one best-selling zinc lozenge. people are surprising themselves the moment realize they can du more with less asthma. thanks to dupixent, the add-on treatment for specific types of moderate-to-severe asthma. dupixent isn't for sudden breathing problems. it can improve lung function for better breathing in as little as 2 weeks and help prevent severe asthma attacks. it's not a steroid but can help reduce or eliminate oral steroids. dupixent can cause serious allergic reactions including anaphylaxis. get help right away if you have rash, shortness of breath, chest pain, tingling or numbness in your limbs. tell your doctor if you have a parasitic infection and don't change or stop your asthma treatments, including steroids, without talking to your doctor. du more with less asthma. talk to your doctor today about dupixent. if your financial situation has changed, we may be able to help. if your financial situation has changed, ♪ her daughter was missing. nancy ekelund began handing out flyers and counting the days without lynsie, ticking them off on little post-it notes. she also went to talk with corrine loomis of the plasencia police department. nancy wanted corrine to know about her lynsie, about how nancy always knew where she was, they were best friends. it was a speech corrine loomis had heard before. >> it's typical with family members when they report a missing person, sometimes they give you the idea that this is an idyllic family life because i think there's a fear that if they don't paint a very rosy picture of this person we're not going to be sympathetic and look for them. >> that you're not going to work hard? >> that we're not going to work hard. and i think there was a little bit of that with nancy. >> plasencia pd was working the case. they brought in the usual suspects, like the boyfriend. >> when you guys were dating, she hasn't been dating anyone else to your knowledge? >> no. >> his name is matthew ramirez. he was at college with lynsie. they had been off and on a bit but then -- >> when i went to her house thursday she was like, i want to break up. >> as can happen with young romance, what was off was soon back on. lynsie and matt were back together in time for the weekend but not in time to make plans for that friday night. >> i'm going to san diego with chris and everybody. i told her have fun, be careful. okay? shez like, okay. >> then in came the last person nobody to have seen her, chris mcamis, 21 years old, out of school. he told the cops he was unemployed. lynsie had met him through friends about four months prior and it turned out he never drove lynsie to andrea's house for a sleepover. chris said that was a lie lynsie made up for her mother. the real plan was to go clubbing all night in san diego. >> she says don't tell my mom we're going to san diego because my mom won't let me go or something like that. and definitely don't tell her that we're clubbing. >> chris told police that when their night of clubbing went bust they headed home earlier than expected. he dropped off the other girls, he said, and then headed to lynsie's house. chris said it was after 4:00 a.m. when he finally got back here to lynsie's neighborhood. and he said that lynsie was worried that her mom might hear his truck pull up at that hour. so chris said lynsie asked to be dropped off not at her house but here at the corner, about 50 yards away. that sounded strange to police until they heard from lynsie's friends that at other times she had asked to be dropped off right here. chris said he then drove home and police even found a photo from a bank atm of what looked like chris's truck heading north on the right street at the right time. to the cops chris's story added up. and that was when police learned matthew and chris were not the only men in lynsie's life. there was someone else both whom matthew and chris had mentioned to investigators, an older man who drove lynsie around. no one knew his name. they had heard lynsie refer to him as her friend. >> all anybody knows him by. >> as her friend? >> yeah. >> nancy had no idea lynsie was friends with any older man. she was about to find out. >> two days after lynsie vistey vanishes you get a phone call? >> yes. >> you're pretty much at your wits' end? >> yes. >> the phone rings and it's marty. >> yes. >> did you know a marty? >> no. >> as far as you know did lynsie know a marty? >> no. >> marty says he went to pick lynsie up from school and she wasn't there. he said he had money for lynsie that she needed for tuition. none of that made any sense to nancy. >> nancy, the mother gets a phone call from a guy named marty. >> marty rossler. >> and what does marty rossler say to her? >> marty says he's befriended lynsie. he's a friend of lynsie's and he's concerned because he hadn't heard from her. >> what did you learn about marty rosler? >> marty rosler was not marty rosler. >> marty rossler was really marty preginzer. he did not have a criminal record. what he did have was a relationship with lynsie that he hadn't told his wife about. he told police he would pick lynsie up and give her rides but that was about it. marty was 58. >> and she was 20? >> she was 20. >> they were boyfriend and girlfriend? >> don't think so. >> so police brought in marty. over two days they recorded those interviews. at times on video and sometimes just on audiotape. >> when's the last time you saw lynsie? >> a week ago now. >> i don't think so. >> absolutely. >> no. absolutely not. >> marty said that he had last seen lynsie the day that she went to san diego on that friday. >> did you believe him? >> we really didn't believe him. >> they didn't believe him because of a tip they had received. a clerk at a local clothing store had called to say she'd seen lynsie and a much older man who matched marty's description together at her store after the day lynsie went missing. >> i flat wasn't there on that day. okay? i have been in that store, all right? and i said -- i'm like you. i'm easily, you know, identified. okay? i mean, probably every place i'd been with her would know that i was in there with her. okay? >> it was a very long interview. >> friendly? >> no. no. i remember drilling down on him because i really thought that he might know where lynsie was. >> you're a parent? >> yes. >> okay. how many kids do you have? >> two. >> if you had a child gone for eight days, vanished, vaporized in thin air, would your heart not be broken? >> oh, absolutely. >> do you not feel some compassion for nancy? >> unbelievable. i think this is a nice girl and, you know, this family's had their share of hard -- you know, hardships. and this is just -- i mean, i feel so, you know, helpless. >> i don't think you are helpless. i think you can help us. >> marty insisted he couldn't, that he didn't know what had happened to lynsie. detectives weren't buying it. >> did you harm lynsie? >> no. no. never. >> even by accident? accidents happen. >> i never touched her. okay? you know, never touched her. >> okay. >> this girl is -- >> have you put her someplace where she's left? >> no. no. >> police searched marty's home and found nothing. no proof that marty had anything to do with lynsie's disappearance. so they moved on to a new suspect, someone closer to lynsie than anyone else on earth. >> "dateline" returns after the break. there are thoughts that are hard to control you're not good enough but i am enough music and i know what i'm made of put your skin in the game with a razor that puts your skin first venus my skin. my way. wow. jim could you ipop the hood for us?? there she is. -turbocharged, right? yes it is. jim, could you uh kick the tires? oh yes. can you change the color inside the car? oh sure. how about blue? that's more cyan but. jump in the back seat, jim. act like my kids. how much longer? -exactly how they sound. it's got massaging seats too, right? oh yeahhhhh. -oh yeahhhhh. visit the mercedes-benz summer event or shop online at participating dealers. get 0% apr financing up to 36 months on select new and certified pre-owned models. tempur-pedic's mission truly transformative sleep. so, no more tossing and turning. because only tempur-pedic's proprietary material adapts and responds to your body- -so you get deep, uninterrupted sleep. take advantage of our best offer of the year, with savings up to $500. hold on one second... sure. okay... okay! safe drivers save 40%!!! guys! guys! check it out. safe drivers save 40%!!! safe drivers save 40%! safe drivers save 40%!!! that's safe drivers save 40%. it is, that's safe drivers save 40%. - he's right there. - it's him! he's here. he's right here. - hi! - hi. hey! - that's totally him. - it's him! that's totally the guy. safe drivers do save 40%. click or call for a quote today. safethe xfinity my account app puts you in control with digital tools to give you the help you need when you need it. get fast and easy answers with personalized help 24 hours a day, 7 days a week. change your wifi password to a phrase that's easy to remember. even troubleshoot your services on your own. we're working to make things a little easier for everyone. download the xfinity my account app today. nancy and lynsie had been together all lynsie's life. now alone nancy waited ticking off the days. in the dark about where her daughter was and about the pace of the investigation. police were not keeping her in the loop. so nancy was delighted when they called to say they were coming to visit. >> you look at the boyfriend, matthew. >> uh-huh. >> you look at marty, the older guy. the relationship nobody knew about. he denies it? >> right. >> you look at chris, he says i dropped her off, i never saw her again. >> right. >> and you look at lynsie's mother. >> we did look at lynsie's mother. you have to. >> so i made my cookies and all this kind of silly stuff. >> coffee, right? >> yeah. >> the cops weren't coming for coffee. they arrived with a search warrant, shovels, and cadaver dogs. >> i was shocked that they even suspected me. i didn't know what even a search warrant was. >> the house nancy and lynsie had once shared was torn apart. >> how much of a suspect was nancy? >> i don't know that nancy was on the radar for a long time. she was on the radar long enough to be able to set her aside. >> after that search they did just that. they believed this anguished mother had nothing to do with the disappearance of her daughter. so they took nancy off the list. they also took off the boyfriend, matthew. he had an alibi that held up, putting him somewhere else at the time lynsie went missing. so that left just two. >> i haven't seen her since that day. >> marty, whom police didn't trust because of his secret relationship with lynsie and because he had lied about his identity, and the man who dropped lynsie off at that corner. the last person to see her before she vanished, chris mcamis. >> go on in here. have a seat there at the end. do you remember corrine loomis? >> yes. >> april 2002, more than a year after lynsie went missing detectives decided to start over. they brought chris mcamis back to see if his story still held up. >> i really would like to think that lynsie has been like either abducted or something happened to her. i'd really rather -- i'd really rather think that she's with friends or something like that. >> police turned up the heat. >> cut the bull and get down to the nitty-gritty. and strip away the i'd like to think in my polyana mind if i lived any perfect world she'd be someplace. okay? >> it's a possibility she's dead. >> right. >> police thought chris seemed oddly calm talking about a friend who may have been murdered. >> if it turns out somebody killed her, what do you think should happen? >> find them. >> when i find them, then what? >> go to jail. >> how long do you think they should go to jail? >> as long as it takes. >> like what? >> go to jail for a while. >> that's as strong as you could get out of him? >> that's as strong as we could get out of him. >> not he ought to go to hell or i'd personally electrocute him? >> i'd personally electrocute him. he should get the gas chamber. she was my friend. she wouldn't deserve that. she wouldn't hurt a fly. there was nothing. >> his lack of emotion was suggestive that perhaps chris should move to the top of the list, but it was not evidence. after the interview chris mcamis was free to leave and detectives weren't any closer to learning what happened to lynsie ekelund. and neither was nancy, who remained convinced her daughter would one day just come home. >> you thought that one day she would walk back through the door? >> yes. >> she believed it because she wanted to and because over the years several people had told her they'd seen lynsie. >> they never saw the front of her face, they always saw the back of her, and i held on to every word they said. >> it was torture for nancy no matter what version of events you believed, and police still weren't telling her anything. nancy, during all this time, feels like she's been sort of cut out of the loop. >> yes. nancy was pretty angry. we worked this case diligently for a long time. at some point you hit the wall. >> at the time there were nine detectives in placentia working everything. drugs, gangs, rape, murder and cold cases. by 2008 it was clear placentia pd had hit that wall. they would need help on this one. and who they needed was a guy named larry. >> tell me about larry. >> larry is phenomenal. >> phenomenal because, what, he sees things other cops don't see? >> phenomenal because he sees things cops don't see. i don't know anybody who could have done a better job than larry. >> the evidence whisperer was about to listen to what the facts of this case were really saying. >> was there something that police had missed? you bet. coming up, that picture of the truck spotted on the night of the crime. something about it just doesn't seem right, but the evidence whisperer is all over it. when "dateline" continues. r 100. now we've created a brand new way for you to sell your car. whether it's a year old or a few years old, we want to buy your car. so go to carvana and enter your license plate, answer a few questions, and our techno-wizardry calculates your car's value and gives you a real offer in seconds. when you're ready, we'll come to you, pay you on the spot, and pick up your car. that's it. so ditch the old way of selling your car, and say hello to the new way-- at carvana. wouldn't iprotected if there was a place that kept you... playful covered fueled ...and safe? well, there is, and always has been. walgreens. everyone's place, for healthy and safe. protect your pet with the #1 name in flea and tick protection. frontline plus. trusted by vets for nearly 20 years. so when it comes to screening for colon cancer, don't wait. because when caught early, it's more treatable. i'm cologuard. i'm noninvasive and detect altered dna in your stool to find 92% of colon cancers even in early stages. tell me more. it's for people 45 plus at average risk for colon cancer, not high risk. false positive and negative results may occur. ask your prescriber if cologuard is right for you. i'm on it. that's a step in the right direction. hello. i'm dara brown. here's what's happening. a black man is hospitalized in serious condition following a police shooting in kenosha, wisconsin. witnesses say the man had been trying to break a fight between two women and was tasered and shot several times as he tried to enter a vehicle. residents along the gulf coast are preparing for a one-two punch. tropical storm marco is expected to make landfall in louisiana on monday. tropical storm laura could hit the gulf coast by mid-week. now back to "dateline." welcome back to "dateline." i'm craig melvin. where was lynsie ekelund? the investigation was at a standstill. detectives had two possible suspects but no evidence linking either of them to a disappearance. enter cold case detective larry montgomery, also known as the evidence whisperer. could he uncover some crucial clues so many others had missed? here again is josh mankiewicz with "the night lynsie disappeared." >> by 2008 lynsie ekelund had been missing for seven years. the case had gone from cold to frozen in time. so placentia p.d. decided to outsource the investigation to the cold case unit at the orange county d.a.'s office, to a guy named larry montgomery. with more than 30 years working homicide, larry's put away his share of bad guys, not usually by knocking on doors. instead, larry works by looking very closely at the evidence. he doesn't work fast. in fact, larry is meticulously slow. and that was just what this cold case needed. >> was there anything in the original investigation that struck you as something that you needed to re-examine? >> everything. >> everything that had led placentia police into that wall trying to decide between two suspects. >> i mean, i'm concerned about this girl, okay? you know. and she's missing. >> marty, lynsie's older friend who kept their relationship a secret and lied about his name, and chris. >> in my heart it seems like she might be still alive. >> the last person known to have seen lynsie when he dropped her off at that corner. >> at that point any idea on your part which of those two was a more likely suspect? >> no. i don't know until i get into it and see the details. >> you're no doubt aware you've got a reputation for believing that -- i don't know if god's in the details but guilt's in the details. >> and innocence. >> guilty or innocent? was it marty or chris? larry even considered another possibility. could it have been random, someone who had seen lynsie at just the wrong time? >> so you've got a bad guy just waiting, hoping that a girl drops out of a car at 4:25 in the morning. >> it happens. >> yeah. you consider that but then you weigh it. and you go, is that a good possibility? probably not but still keep an open mind. >> so larry sat down and read through the entire case file. all the witness statements, all the interviews. he did that for two years. >> we're going down this dead end road again. >> he watched the february 2001 interview that police did with a very unhappy marty. >> doesn't it strike you as tremendously suspicious that marty would call after lynsie disappears, talk to lynsie's mother and give a phony name? >> if you didn't know the background of marty, then absolutely. >> when i talked to the mother on the phone, i gave her an identifier, okay? named marty resler, that's what i said. >> which is a lie? >> which is a lie. >> watching that interview, larry chalked up marty's dishonesty as an attempt to save his marriage. >> i don't want my wife to be brought into this thing. >> larry also took a closer look at the idea that marty and lynsie were together at that clothing store after she went missing. >> i flat wasn't there on that day, okay? >> no one ever found any security video of that and larry's learned over the years that well-meaning people often get dates wrong. and larry learned a key fact. marty had actually participated in those early searches for lynsie. >> you eliminated marty fairly quickly then? >> yes. >> marty's behavior matched up with that of an innocent person, not with a guilty one? >> that's correct. he is actually doing exactly what you would o'if you were look for lynsie. he was searching. >> so larry montgomery turned his attention to chris mcamis. guilty or innocent? chris was the last person known to be with lynsie. he told police he drove straight home after dropping lynsie off. and police found that photo of what looked like his truck heading north away from lynsie's neighborhood, which took him past this atm camera. >> the video from the atm camera, police at the time saw that as not ironclad proof that chris was telling the truth but suggestive that what he said he actually did. >> correct. >> but when larry compared photos of chris's truck with the photos from the bank, he saw something no one else had noticed. the paint on the back of the side view mirrors on chris's truck was white. >> what about the truck in the photo? >> truck in the photo had a dark spot in that area, which means whatever mirrors were there if there were mirrors there they were black. >> so it's not the same truck? >> that's right, it's not. >> suddenly chris's alibi had a big hole in it. larry moved on to chris's history with women. two ex-girlfriends talked to police about how chris would become unhinged by rejection, or what he called disrespect. larry heard about how chris had once crushed a pet crab with a hammer right in front of one of his girlfriends because he thought the crab had killed one of his fish. >> this is a guy with some significant anger issues. >> it certainly appears that way. >> he told me it was from a car president. >> larry listened to chris's interviews and caught him talking some of the time about lynsie in the past tense. >> her hand was pretty much stuck like this. >> okay. >> then larry found something in the paperwork from placentia p.d. that proved chris mccamis had lied to the police early on about his whereabouts on saturday february 17th, the day lynsie didn't come home. chris had told the cops he stayed close to home, but larry checked chris's credit card statement. >> there was one entry on february 17th and it turns out it was santa clarita, which is 50 miles north of where chris lived. >> why would chris be in santa clarita? >> well, that's what i wanted to know. >> digging through the reports, larry found information about chris's dad, that he was in construction and that in 2000 and 2001 he had a job site in santa clarita. >> you can't tell now, but back in 2001 this was a major construction site. now, chris had told police that he did not work for his dad that winter, that he was on unemployment, but larry saw some big cash deposits going into his bank account in addition to his unemployment checks. so he thought chris may have been working for his dad off the books. and larry came up here to ask around. >> and they told you it was chris's father's construction company? >> chris's father did some of the tractor work at that site. >> and chris worked there? >> and chris was one of the tractor drivers that the superintendent said was there ever day. >> is this where you thought to yourself, that's where lynsie ekelund is? >> i thought chances are excellent that if i'd killed lynsie and i was in chris mccamis's situation and i had use of a tractor out in the middle of nowhere, i might use a tractor to dig a hole to put her in. >> now all the evidence whisperer had to do was prove it. coming up, an undercover operation. >> were you armed? >> yes. >> and you were wearing a wire? >> yes. >> when "dateline" continues. ♪ here's to the duers. to all the people who realize they can du more with less asthma thanks to dupixent, the add-on treatment for specific types of moderate-to-severe asthma. dupixent isn't for sudden breathing problems. it can improve lung function for better breathing in as little as 2 weeks and help prevent severe asthma attacks. it's not a steroid but can help reduce or eliminate oral steroids. dupixent can cause serious allergic reactions including anaphylaxis. get help right away if you have rash, shortness of breath, chest pain, tingling or numbness in your limbs. tell your doctor if you have a parasitic infection and don't change or stop your asthma treatments, including steroids, without talking to your doctor. are you ready to du more with less asthma? talk to your asthma specialist about dupixent. if your financial situation has changed, we may be able to help. if your finagot it.ituation has changed, nooooo... nooooo... quick, the quicker picker upper! bounty picks up messes quicker and is 2x more absorbent, so you can use less. bounty, the quicker picker upper. ♪ but come ye back when su-- mom, dad. why's jamie here? it's sunday. sunday sing along. and he helped us get a home and auto bundle. he's been our insurance guy for five years now. he makes us feel like we're worth protecting. [ gasps ] why didn't you tell us about these savings, flo? i've literally told you a thousand times. ♪ oh, danny boy, the pipes, the pipes are calling ♪ i'm just gonna... ♪ from glen to glen i'm just gonna... did you know you can shorten your cold [♪] with cold-eeze® lozenges. cold-eeze® can shorten your cold by 42%. it releases zinc ions that some scientists believe inhibit cold viruses from replicating. try cold-eeze® the number one best-selling zinc lozenge. it was october of 2010, nine years after her daughter disappeared. nancy ekelund was still waiting and doing what she could. she was now at 3,535 days without lynsie. she didn't know it, but a few miles away larry montgomery was tightening the noose around chris mcamis. larry had recruited a motorcycle cop from a nearby town to go undercover. >> they needed a police officer who looked like a college student and didn't have the mannerisms of a police officer. >> spring sandelli was that officer. >> how were you dressed? >> jeans on and just a little shirt. something that a college student would wear. >> were you armed? >> yes. >> and you were wearing a wire? >> yes. >> hi. are you chris? >> yes. >> hi. my name is nicole anderson. i'm from fullerton college torch magazine. >> officer sandelli was posing as a student reporter complete with a phony press pass. she knocked on chris's front door. chris had talked to a student reporter from lynsie's college in the past about the case. >> did you use your real name? >> no, i used a fake name. told him who i was. and -- >> we just received word at the torch magazine that remains have been found that they believe belong to lynsie. so i guess they're doing dna testing right now and in the meantime i'm supposed to go contact friends, family to get their initial reaction for a story. >> okay. >> when i told them that the police believed they found lynsie's remains his demeanor changed. >> how? >> quite drastically. i could see the color in his face went white. >> the police had not found lynsie's remains. that was a lie. police do it all the time and it's legal. in fact, larry had tried to find lynsie up at the construction location where chris had worked and he had gotten some interest from cadaver dogs but nothing more. just down the street from chris's house bryce angel of the >> so you're watching him while this interview happens on his front doorstep? >> yeah, i was sitting ten houses down watching the reporter, or the undercover police officer. once she left the area, we were in business. >> what happens? >> later that night he was seen coming out of his house and going into the garage. lights go on, and we're talking like 3:00 in the morning. it was clearly a sign of somebody who couldn't sleep. >> detectives were sure they'd rattled their suspect. the next day they trailed chris when he left his house. >> at some point it became apparent that he knew we were following him. >> they broke off surveillance. and brought chris in. >> chris, have a seat. >> larry had read all about chris mcamis, and he'd looked at tape of every time chris had been in for an interview. >> here's what the situation is. >> today he and chris were going to meet for the first time. >> i have been investigating this case for about two years now as a cold case investigator. >> larry had a plan to get chris to talk without asking for a lawyer. >> you probably want to know what's going on, what's happening, why you're sitting here. >> larry promised to fill him in on the case in detail, thinking chris would want to know if the cops had the goods, and then maybe he'd have something to say. >> i do have to advise you of your rights, which i will do in a moment. then i'd like to explain to you everything. >> larry read chris his rights. and then before chris could really respond, larry laid out his case. he said he knew chris had never dropped lynsie off that night. because the atm photo that at first fooled investigators actually proved chris wasn't there. >> it wasn't your truck. but for years, it was thought of as your truck, but it's not. as a matter of fact, your truck did not go by that night. it wasn't there. >> he told chris about the credit card statement and how he found someone who remembered chris working on the job site. >> all of a sudden, big red flags, you are working. you are up there when you said you were not. but he said you guys don't work on saturday. lynsie disappeared on a saturday morning. none of your credit card usage up there is on any weekend. all of it's on weekdays, except for the day lynsie disappeared. so you're not up there working that day. >> he told chris the lie about lynsie being found. >> we went recently, got dna from mother and dad and had that checked against the body. and it's lynsie. now we've got lynsie up in the area where you were, right at the time where you did not drop her off. and we have enough to prove the crime. >> and knowing about chris' anger issues with previous girlfriends, larry summoned up a little empathy to draw chris in. >> i know you have that ability to be angry, but i don't know what would cause her to get you that angry, or what she could have done. >> chris didn't say much until a little body language revealed that larry was on the right track. >> was it a premeditated thing? i don't think it was. so what did she do? larry finished talking. he was hoping chris would give it up. >> i think i need a lawyer to talk to you about this with me. >> it's up to you. >> the supreme court has made it pretty clear. if someone declares that they want an attorney, the interview is supposed to stop until one can be hired or provided. but in this case, larry was walking a line. believing that asking for a lawyer isn't the same as wondering if you need one. corrine loomis was watching from another room. >> that's about as close as you can get to the "i want a lawyer" line without actually saying it. >> right. >> were you holding your breath when he said that? >> yes. this was a make or break interview. if he didn't confess, he was going to walk again. >> coming up -- it's pretty inspiring the way families redefined the word 'school' this year. it's why, at xfinity, we're committed to helping kids keep learning through the summer. and help college students studying at home stay connected through our university program. we're providing affordable internet access to low income families through our internet essentials program. and this summer, xfinity is creating a virtual summer camp for kids at home- all on xfinity x1. we're committed to helping all families stay connected. learn more at xfinity.com/education. i need to know what occurred so i do the right thing, because something happened to her. >> larry montgomery spoke for 45 minutes. he'd given chris mcamis everything he had. >> take a look at the credit card usage. >> the photo, the job site. >> how long did you know lynsie? >> this is not a very convenient time right now. >> the phony story about finding the body. and then the interview had suddenly stopped dead. >> i think i need a lawyer to talk to you about this with me. >> well, it's up to you. >> and because chris said i think i need a lawyer and not i need a lawyer larry thought whatever came next would be admissible in court. detective angel who'd been letting larry do the talking then spoke up. >> i knew that was a moment of truth, i had to interject something very quickly. >> chris, nobody likes to be labeled a monster. and in this case, that's the way it's pointing. only you have the other side of the story. nobody is going to be able to speak for you. that's why we're here now. >> that's it. >> there's a reason everything happens. i'm sure there were some circumstances that happened that night or that morning. >> he kind of sighed, and he laid out a story. >> all right, what happened was -- >> and suddenly, you realize -- >> this is it. he's going to give it up. i was sitting next to the detective from the other agency, and i reached over and grabbed his arm and i said, he is going to confess. >> it was sad, and it was ugly. >> she -- i was going to take her home. >> okay. >> she was telling me, why don't i just sleep over at your place, because i don't want to upset my mom. >> makes sense. >> as larry had suspected, chris never dropped off lynsie at that corner. >> i was trying to kiss her. and then she elbowed me in the chest. and then i went to my -- i went to my kitchen in my apartment. and i drank a lot of vodka. and then i went back, and i tried to do the same thing. >> okay. >> she pretended to be asleep. and i pulled her pants down and i was totally drunk. >> okay. >> she got up, said oh, my god, what are you doing? i'm calling the police. when i got up and walked to her, she tried to knock me out with my phone, with my home phone. >> did she -- >> to my face, yeah, she, like this to my face. >> okay. >> and being drunk, it enraged me. it set me on fire. and i grabbed her, throw her onto my bed, and i got her into a head lock. >> okay. >> and she died. >> then what did you do? >> then i tried to figure out what i should do, because i couldn't believe how it just happened that way. >> quickly, huh? >> it just -- i couldn't believe it. i thought she was just going to pass out, and i ended up killing her. >> that was it. lynsie had been killed before anyone realized she was even missing. chris says he then drove up to the work site and used a skip loader to dig a hole. he held on to lynsie's body for a few days, and then when no one was around, he buried her. >> did it feel better to finally know? >> no, because i was really devastated. there was a relief, but i wasn't any happier because of it. >> after the confession, detectives left chris in the interview room with another detective to watch him. and chris simply could not stop talking. >> unbelievable. >> what's that? >> it's been so long, it finally feels better when you finally just say what you were supposed to say, you know? i know my life is ruined now. >> do you know if i'm going to get the death penalty for this? >> you're going to have to ask them those questions. >> then larry came back. always meticulous. he wasn't done. he wanted that final detail. >> where approximately was it that you dug the hole to put her? >> where exactly chris had left lynsie. >> right up in here? >> he explained to chris, that even though they found her remains, which wasn't true, the grave site had shifted over the years from flooding. >> this is where the tractor was parked and where exactly you dug the hole? >> with the detectives, chris returned to the site that had become lynsie's final resting place. >> right where this tree is, i pulled my truck over and parked it. >> this tree to our left here? >> uh-huh, right where this tree is. it didn't used to exist there when we had construction. >> okay. >> he wasn't sure of the exact spot. >> it's over in this vicinity. >> but it could be way up there or way over here? >> from that tree all the way to that brush. >> that brush over there? >> it took more than a day of digging to find what was left of lynsie. first they found a shoe, then a jacket. and a bracelet. that's how nancy knew they'd found her. the coroner confirmed it using dental records. >> the back of my truck was over here. >> two years after he confessed, chris mcamis pleaded guilty to second-degree murder. his sentence is 15 years to life. >> you told me that you thought you'd let this consume your life too much. >> oh, it did. it does to this day. >> well, now it's over. what are you going to do? >> i don't know. a new life is opening up to you, and i don't know. i don't have any answers. i just have to get over this. that's all for now. thanks for joining us. mystery on the missippi i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." >> very bubbly personality. a huge smile. a child's worst nightmare. to lose a mom. every day i wanted answers. every days was told it was unknown. people just don't die. >> she was a loving mother. he was a crime fighting prosecutor. you are a pillar of that community? >> i did what i thought was right. >> then one day the law was at his door. his wife was dead, in bed. >> her eyes were opened, she was pale.