>> go get him. go get him now. >> a neighbor with a gun and a grudge. >> i thought, "they better get to him before i do." >> but some said this couple was having trouble. that seth had a secret. >> did he tell you, "she sent me some topless pictures"? >> yes. >> others said the real murderer was someone else, right under cops' noses. >> a legitimate suspect that should have been investigated. >> a case unfolding on camera. one that would test three juries. shatter two families. >> just like somebody hit me in the stomach. >> and take one final twist. >> that was her biggest secret. >> i'm lester holt, and this is "dateline." here's dennis murphy with "before dawn." >> reporter: the cornfields of iowa. are a far piece from memphis. iowa, a baby girl was named after a princess. lisa marie. yup, that one. >> as a kid, i was pretty big into elvis. i knew that my first daughter was going to be lisa marie because of elvis, of course. >> reporter: just as todd caldwell hoped, his little lisa lived up to her big name. >> she was just the life of the party. >> once she started talking, she hadn't shut up. >> reporter: they're divorced now but tracy and todd caldwell watched their girl grow up all but unstoppable. a vivacious, winning teen. bowling, todd, we're not just talking recreational saturday night now and then? >> no, we're talking about a state champion bowler. anything she did, she had to be the best at it. >> lisa, look over here. >> reporter: lisa was a teenager when her parents divorced. todd remained an active father to lisa and his three other children. all the while, he was working a stressful and dangerous job as a deputy in the wapello county sheriff's department. he found comfort in several ways. one was his occasional hobby. he'd take out his sketch pad from time to time. and then he met and fell hard for a nurse named amy. before long, he was starting fatherhood all over again. with twin daughters. this time he was getting lots of help from lisa. she was the twins' default babysitter. >> she was more hike a second mom to the twins than a big sister. >> she was just a caregiver to anybody. >> reporter: you had a very close relationship? >> uh-huh, very. i would get into bed with her. we'd watch old episodes of the "golden girls." [ laughter ] >> reporter: that's a sweet relationship. >> yeah, and she always says that i was dorothy because i'm such a grouch all the time. [ laughter ] but yeah, that was my favorite time with lisa. >> i'm so lucky. >> reporter: but step-mom amy put on her enforcer hat when it came to lisa's teenage romantic life. >> i wanted to know who the boyfriends were. i wanted to know who their parents were. i was the one that they had to pass the test with. >> reporter: the boyfriend who passed with flying colors was a kid named seth teckle. he came from a long time local family. his grandfather was the mayor. the dad owned a local bowling alley. the bowling alley was where seth as a young teen began noticing lisa. his dad was her high school coach and seth bowled almost but not quite as well as lisa. the two worked part-time together at the lanes. they were becoming boyfriend/girlfriend and that was fine with both families. >> you liked this young girl? >> a lot. >> she was a part of our family. >> reporter: the teckles were a church going family and seth's mom remembers the compassion shown on a relief mission to katrina. >> he just would talk to the folks for hours and hours. they became very good friends. i have a lot of memories like that of seth. >> helping people. >> yeah. >> reporter: and lisa wanted to help people too. she followed her father into law enforcement first as a reserve deputy and then as a jailer in a neighboring county. >> i told her that she would have my blessings if she wasn't just an average cop. i wanted her to be a really great cop because i didn't want to have to worry about her inefficiencies maybe endangering her life. >> reporter: after years of hearing patrons at the bowling alley joke object when the two of them were going to get married, seth and lisa made the inevitable official. >> how did you find out they were getting hitched? >> seth actually came to our house and met with us and asks us our permission to marry lisa. old school. >> old school. >> reporter: after dating for seven years, seth and lisa got married in october 2011. she was 22, he was 21. >> i just told him that, no matter what he did, to take care of her and protect her. >> and he said? >> he said he would. >> she got much more than a brother-in-law with seth. >> he was my best friend and he was that other person that i could always go to. >> he called me dad. we told each other we loved each other. we hugged every time we left each other. i felt as close to him as i did my son. >> reporter: for lisa, it wasn't just gaining a husband. it was having all his buddies come along too. a package deal. >> so how did lisa put up with you guys? >> she was interested in the same things that all of us were. she liked to go fishing. she liked to go hunting. she liked to shoot guns. >> was she okay? >> better than that. >> sounds like you would have been happy if she were your girlfriend? >> seth was lucky. >> lucky for sure. but seth knew it was time to settle down and get a real job. like lisa, he was drawn to uniformed service. he signed on as a volunteer firefighter and drew a paycheck as a security guard. but his father-in-law todd was helping him get a higher rung on the ladder with a soon to start job as a jailer for the sheriffs. >> they were very close. todd was a big influence on seth. that's why i think he went into law enforcement. >> reporter: now more changes for seth. he was going to be a father. they picked a name for the unborn girl, zoe maria. in may 2012, they were halfway through the pregnancy. >> seth and lisa, a baby on the way, were starting out their married life in this humble little trailer. it was a gift from his dad purchased on a beautiful piece of property. a starter home to save money for the future. the only apparent cloud in the picture was an escalating feud with aac there was bad blood. >> reporter: it happened at 5:00 in the morning. a sudden horrifying sound that shattered two young lives. >> 911. what's your emergency? >> reporter: saturday, may 26th, 2012. memorial day weekend. >> not breathing. >> does she have any medical problems? >> she's been shot. >> a shotgun blast that ended all the plans of mr. and mrs. seth techel. >> newlywed, mom-to-be, and now, out of the blue, victim of a violent attack. who would want to hurt lisa? when we return, deputies race to the scene, where the shooter could be lurking anywhere. >> you didn't know if somebody could have winged a shot at you? >> yeah, that was possible the whole time. 6x the cleaning power, even in the quick cycle let's go did you just get up uh-huh it's got to be tide it's my decision ito make beauty last. roc® retinol, started visibly reducing my fine lines and wrinkles in one week. and the longer i use it, the better it works. retinol correxion® from roc. methods, not miracles.™ (crunching) ♪ dude, your crunching's scaring the fish. dude, they're just jealous. kellogg's raisin bran crunch... ...with crunchy clusters and the taste of... i guess we're having cereal for dinner. deliciously heart-healthy kellogg's raisin bran crunch. ♪ ladies and gentleman this is a robbery. what are you doing after this? ♪ we danced in a german dance group. i wore lederhosen.man. when i first got on ancestry i was really surprised that i wasn't finding all of these germans in my tree. i decided to have my dna tested through ancestry dna. the big surprise was we're not german at all. 52% of my dna comes from scotland and ireland. so, i traded in my lederhosen for a kilt. ancestry has many paths to discovering your story. get started for free at ancestry.com. >> reporter: it was the end of a long overnight shift for sheriff's deputy marty wonderlin, the only deputy on duty in wapello county, iowa. all was quiet and with the first hint of daybreak that saturday morning, marty relaxed and turned up the music in his cruiser. >> it's the ragged end of the shift for you? >> yeah, i'm taking my last little loop around the county and going to watch the sun come up and go home and go to bed. >> reporter: that plan came to an abrupt end around 5:30 a.m., when seth techel made a desperate 911 call from his house. >> she's been shot. i'm going to [ bleep ] kill who -- i was getting ready for work and i heard a gunshot and i came running out and she was shot in the side. >> reporter: dispatch relayed the message to marty wonderlin. the young deputy had never gotten a call like this. >> i have a report of a lady not breathing. i have now been advised this lady's just been shot. >> is your heart -- heart pounding a little? >> oh, yeah. that's an understatement. >> reporter: with his car and his mind both doing 90, marty raced to the house in under ten minutes. he slowed along the rise of the gravel country road and stopped in the driveway. he had no idea what he'd be facing. his dashboard ra the scene as he approached the house. >> here's how you get in the trailer. what do you see, right about here? >> you could see seth techel up on the porch. he was wearing cargo shorts and a belt, and he just bent over, you know? >> what's he doing? >> sounds like he's crying, just sobbing. >> reporter: the toughest call of marty's career was suddenly so much more complicated. he knew the grieving husband on the porch, considered him a friend, knew his wife lisa too. and her father, todd, was a respected, fellow deputy. the unfolding tragedy had just become very personal. >> reporter: deputy, how do you set your brain in compartments, where you got to be very professional? this is the first time you've had a major crime, and yet it's also people you know? >> it's tough. >> were you scared? it's okay if you were. >> yeah, definitely was scared. you know, concerned about a lot of different things. >> yeah, i mean, that was possible the whole time. >> reporter: as the only cop at a dangerous, chaotic scene, the possibility of a live shooter still on the grounds, marty's adrenaline was pumping. when he entered the trailer, a paramedic was attending to lisa. she was lying in her bed. it didn't look good. marty's only thought was to help her, but he had to secure his rifle, so he ran back to his cruiser to lock it up. >> i got on my radio and i think i told dispatch, "get 58 out here." >> call 58 and have him get out here. >> reporter: badge 58 meant deputy todd caldwell, lisa's father. >> in hindsight, i wish i wouldn't have done that. i wish i would -- >> why do you say that? >> well, because i saw a lot of things that morning and now because of me, because of asking him to, you know, come out there, he's going to have to live with some of those same images that i do now. >> reporter: todd caldwell was asleep, but his cell phone was plugged in next to the bed, always ready for a middle-of-the-night emergency call. >> we get a call from, you know, a dispatcher i've known for 20 years and i can tell that his voice is different. and from what i remember, he just said, you know, you need to get out to lisa's house. she's been shot and isn't breathing." >> reporter: todd's wife amy bolted out of bed. her step-daughter, her best friend, needed her. >> i kind of left him behind. i didn't put shoes on, didn't have socks on. i went in my pajamas and drove 90 miles per hour, you know? i'm an e.r. nurse. i'm thinking -- >> you're sort of in nurse mode there too? >> yeah, i'm thinking, "well, you know, maybe if i get there fast enough -- >> minutes matter. >> there will be something i could do. >> reporter: todd raced behind in a separate vehicle. >> i just repeated over and over, you know, "oh my god. oh my god, oh, my god." i just remember that's all i could think and say is, "oh, my god. oh, my god, oh, my god." >> reporter: at the scene, deputy wonderlin ran back to the house and did what he could to help the emt. >> started giving lisa cpr, so the paramedic could -- i think he was getting, like, a defibrillator ready. it felt like forever. you know, and i'm asking him, you know, "you want me to do cpr still?" he told me not to. >> reporter: there was nothing more to do. she was gone. along with her unborn daughter. lisa marie techel was just 23 years old. >> i ran in there and you could tell that she was gone. >> so you went into the bedroom? you saw her? did you tend to her? >> yeah, i held her hand and i rubbed her belly and i just said, "my lisa, my lisa." >> todd, did you go into the house? i hope not. >> yeah, i did. i went in there and i seen her laying there and i seen the amount of blood that was on the bed and i knew, from my experience, that was too much blood to sustain life. when i listen to like the tape recording of it, i hear myself bellowing. i don't know how to describe, but i don't even remember doing that. >> what happened? >> rep marty wonderlin had a job to do. >> end of your shift, your first homicide. so you're in the barrel here. >> got to start working it. >> reporter: there was an immediate lead from, of all people, todd caldwell. the veteran cop, who had just seen his precious daughter lying dead in a pool of blood, said he knew who the shooter was. and in a voice filled with rage, he told his fellow deputies to take the suspect down. >> that [ bleep ]. go get him. go get him, now. >> coming up -- who was todd caldwell talking about? turns out there was someone in seth and lisa's life who had everybody worried. >> things were escalating. they were fearful. i was fearful. >> when "dateline" continues. for 100 years, heritage and innovation have made gillette the #1 shave in america. now get gillette quality at lower prices -- every day. brought to you by 1200 workers in boston -- we're proud of giving you our best. gillette. the best a man can get. ♪ ♪ start the car! start the car! inter sale. wooooooo! get up to 50% off select items. now through january 10th. ikea. ♪ ♪ start the car! start the car! the ikea winter sale. wooooooo! get up to 50% off select items. now through january 10th. ikea. >> reporter: lisa techel was dead, murdered in her own bed. her distraught husband seth was outside, shirtless and barefoot. when lisa's little sister presley arrived, all she could do was try to comfort him. >> by the time i got there, they had stuff taped off. and i went up and i just gave seth, like, the longest -- it seemed like the longest hug ever. >> your best friend. >> yup. >> reporter: seth was inconsolable and acting out. >> i went over to him when i first got there and i tried hugging him. he pushed me away. he punched his truck, and i said, don't do that, seth. you know, let me see your hand. >> reporter: todd offered to take seth back to his house, but doug techel knew this was a moment his son should be with him. >> it was just bad. i mean, it -- he was sobbing. and we just hugged and cried. >> reporter: marty wonderlin, working his first homicide, was the first deputy to speak to seth. happened. >> i came running out. and i looked in the bedroom and she's just [ bleep ] laying there. >> reporter: through the overwrought husband's sobbing, a story started to emerge. >> he basically tells me that he was in the shower getting ready to go to work and he hears a gun go off. >> i ripped open the [ bleep ] shower curtain and i grabbed my towel and i came out. i didn't see anybody down the hallway. i'm going to kill who [ bleep ] did this. >> reporter: there's been some sort of an intruder. >> yeah, that's what he's telling me, that someone came in while he was in the shower, shot lisa and ran away before he could catch him. we'll figure it out, brother. >> i can't [ bleep ] tell todd. >> we'll figure it out. >> reporter: lisa's father todd thought he'd figured it out and already had a suspect. >> that [ bleep ]. go get him. g now. >> reporter: todd's rage was directed at the neighbor on the other side of the fence topped with barbed wire, a 56-year-old disabled army veteran named brian tate. >> i just remember saying, "go get him. go get him now," and i thought, "they better get to him before i do." >> reporter: brian tate had been embroiled in an escalating feud with his neighbors lisa and seth. todd knew all about it and was certain his daughter was now dead because of it. this is this culmination of bad blood's been going on for a month's time or more now? >> right. uh-huh. >> reporter: it started about two months before the murder. seth pulled a dead deer off the road along the property line. brian tate later tossed the hide onto seth's property. seth tossed it back, and the battle was on. tate made several calls to the county, complaining about nasty acts of vandalism. todd caldwell responded to one in april. and tate pointed the finger at his young neighbor. >> i can't remember names. >> seth, seth techel. >> seth techel >> torkel? >> techel. >> techel. >> yeah, his dad owns champion bowl. okay. >> and i'll tell -- i just -- they're good people. they really are. >> reporter: now this guy, brian tate, does he know that you're the father-in-law of the neighbor? >> no, and i don't want to tell him that because i don't want that to affect maybe what he does or doesn't do. >> and he thinks that's the source of his trouble? >> right. >> reporter: those people over in the trailer property across the way? >> yeah. >> well, if you can, let us deal with it. >> what if -- what if -- what if i'm the one who's gotta catch him? >> reporter: brian tate told todd that dog feces and rocks had been hurled at his home. he then showed todd the evidence. he described the vandalism of his home in stark terms. >> he says that he thinks these are acts of terrorism and, you know, kind of a bell goes off like, terrorism's kind of a weird word to use. and the whole time -- half the time, i guess, he's sitting there. laying on the ground. i'm like going, that makes me feel a little -- >> does that make you feel a little twitchy? >> yeah, yeah. exactly. >> reporter: so twitchy that todd sent a heads-up e-mail warning fellow deputies about tate, that he might be dangerous. >> i'm thinking, i don't want to be the reason a deputy goes out there and gets hurt. okay, if you go out there, be careful. tate might be 1096, which means mentally, you know, challenged. >> reporter: in fact, tate did have a history of mental illness. he'd been diagnosed as a paranoid schizophrenic. seth's mother lorraine, a social worker used to dealing with mental patients, was worried and talked to both seth and lisa about their neighbor. >> she was terrified. this was when things were escalating. they thought that they could, you know, handle whatever. and -- but they were fearful. i was fearful. >> reporter: on may 15th, just 11 days before lisa was killed, an agitated tate made another call, complaining that the vandalism -- the terrorism -- was getting worse. todd responded again, this time accompanied by fellow deputy don phillips. >> i'm trying to have a conversation with you. you know it? >> i don't want to be yelled at either. >> well, i'm trying to have a conversation with you and i don't understand why you're walking. >> you're raising your voice at me. >> i -- you're right. i am. >> what i'm wondering -- >> because you're not listening. >> did you think he was a risk, that this was -- >> yeah. yeah. >> a guy who was capable of flipping out? >> i did. i did. >> reporter: and now, lisa was dead, and the trailer was a crime scene. marty wonderlin, the first deputy at the scene, already knew all about brian tate and had zeroed in on him as his candidate for prime suspect. all the direction is heading across the fence to this guy whose name is brian tate. >> it is. >> reporter: and police decided it was time to pay a visit to tate. they armored up and got out their long guns, not knowing what their suspect might do. >> if you're ballsy enough to break into a house, shoot lisa and make it back out, you're anything. >> coming up -- cops confront their man. >> i had my rifle out, locked and loaded. that's because one gain flings pac has more freshness than a whole bottle of the other guy. gain. seriously good scent. ♪ ♪ohhhhhh, ou! guess what i just got? 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'k, well we'll just- phone: hey sorry. i had you muted. well yea let's just- phone: so what i was thinking- ok well we'll- phone: yeah- let's just go ahead- phone: oh alright- the award-winning geico app. download it today. >> reporter: on the main street of tiny agency, iowa, bad news traveled fast. a pregnant woman was dead and a gunman was on the loose. just as quickly, fear took to roost. >> the 23-year-old reserve sheriff's deputy was shot and killed at her home in the town of agency. she was five months pregnant. >> reporter: lisa's murder was the first in the farmtown in 15 years. deputy don phillips, seen here unspooling crime scene tape, had a personal stake in cracking the case. lisa's dad is one of his best friends. >> todd and i began the same year at the sheriff's office together. i watched lisa grow up. i just reassured him that we'll figure this out. we'll find out who did this. >> so whatever's happened here is really within your family, the law enforcement family, the county? >> correct. we're a small sheriff's office. we know everybody. we know each other's kids and extended families. >> reporter: and they also knew something about that guy next door, brian tate. ever since the first deputies arrived at sunrise, they'd been peeking across the barbed wire. just how dangerous was this fussing neighbor? were they another shotgun blast away from finding out? at 1:00 that afternoon, eight hours after lisa was shot, deputy phillips and a team of investigators were ready to confront the neighbor. >> so the decision is made. we've got to talk to brian tate. >> yes. he was definitely a person of interest that we need to go talk to. >> did you put your body armor on? >> yes, i did. >> reporter: marty wonderlin did, too. he was preparing for anything, even a shootout. >> we got strapped up. we're all ready. ready for business. >> reporter: marty was in the backup car, while deputy phillips and a partner drew line of fire detail, approaching brian tate for an interview. >> he's our prime suspect. it's very possible in all of our minds that he just shot and killed lisa. >> reporter: as the phillips team walked slowly up to the tate house, marty and the chief deputy provided cover in the driveway. >> i had my rifle out, locked and loaded. had the red dot turned on. everything's popped off. we were ready. >> reporter: nerves screaming, everyone was poised for battle, everyone but, it turned out, brian tate. he wasn't armed or belligerent. they could all exhale. >> as we walked up there, he was accommodating, got some chairs out for us. >> this is brian tate? >> brian -- brian did. and we sat down in his front yard. >> reporter: in the front yard in lawn chairs, his mother and no shotgun in sight. so the cops turned on a recorder and started asking questions. >> so you asked him 5:00 a.m., where were you? >> yes. >> reporter: he said he was in bed in his basement bedroom, sleeping off a higher dose of medication for his schizophrenia. >> i went to bed about 8:30. >> right after i did. >> yeah, after mom did. fell right asleep. didn't hear nothing. didn't get up till 11:00. >> reporter: he said he was still asleep when the shooting must've happened before dawn. tate's mother corroborated his 15-hour sleep alibi, though the cops knew full well that mothers can often be biased witnesses. >> did you hear anything in the middle of the night last night or see anything? >> i was in bed and normally i would've been up doing guard duty with all this [ bleep ] that's happened, but i'm schizophrenic paranoid. >> reporter: guard duty. the ex-military man called himself a sergeant major and walked the picket on his property line, vigilant ever since his property had been littered with dog feces, his barn pelted with rocks. deputy don phillips knew all about the vandalism complaint he and todd caldwell were the deputies who'd responded to tate's house just 11 days earlier. they'd downplayed his complaints then and thought he was a crank off his meds. >> you said earlier, brian, that you, you'd sit outside here. >> at night? >> at night, yeah. when's the last time you did that? >> oh, it's been a good week or so. >> week or so? >> they don't want me to do guard duty anymore. they want me to get sleep, take more medications. >> you were such a calm quiet guy until this vandalism started, and then you're just like a different person. >> i was mr. nice guy for a long time. it done me no good. people took advantage of me, so i'm kind of taking a different approach to life right now being more serious and more not such a nice guy. >> reporter: after venting about the vandalism, the 40-minute interview was over. but investigators weren't done. they'd be back to question tate again. >> so what'd you think you had when you got back in your vehicle? >> we still had a whodunit in >> reporter: but lisa's step-mom and sister had no doubts whatsoever. >> i thought it was brian tate. >> reporter: but investigators knew they still had to talk to the husband. when agents scheduled an official interview with seth for that same day, it didn't sit well with amy. >> is this how you -- how you always treat grieving husbands? and i started crying. i'm there thinking, they're being so mean to me. >> we kind of got into an argument because i'm like they have to do that. >> reporter: would-be cop seth techel agreed completely. he knew the spouse had to be ruled out. he said he was eager to get seth crossed off the suspect list as soon as possible. so he went downtown and instructed his parents no lawyers. >> you remember saying do we need to go get a lawyer? >> he was adamant. he said no. >> he said i didn't do anything. >> i have nothing to hide. >> i don't need a lawyer. >> reporter: was that a mistake? seth had told his story to one the scene. but now, he'd be talking to an elite state interrogator, and the tone of the investigation was about to change. >> coming up -- deputies learn that seth may be hiding something. >> i told 'em that seth had a track phone. >> so kind of a secret phone, huh? >> yeah. >> when "dateline" continues. ad. 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[ flo laughs ] [ plop ] oh! jeez. ♪ for the irresistible taste of ctemptations treats.g oh hey, check this out. temptations. cats can't resist. ♪ ♪ start the car! start the car! the ikea winter sale. wooooooo! get up to 50% off select items. now through january 10th. ikea. ♪ ♪ start the car! start the car! the ikea winter sale. wooooooo! get up to 50% off select items. now through january 10th. ikea. >> reporter: todd and amy returned home, destroyed. and the longest day of their lives wasn't even half over. >> my remaining kids, i know they're going to be horrified and i don't even think about myself at that point. >> reporter: but todd was thinking about the son-in-law he loved like his own boy. seth had agreed to go downtown for a formal interview without a lawyer. by now, the county deputies had called in state agents from the dci, iowa's division of criminal investigation. it became a shared investigation, the dci providing forensic resources and expertise, the deputies offering local knowledge and manpower. dci's tony birmingham was lead agent. he hand picked fellow agent chris thomas to interview seth. >> there was no doubt in my mind that chris was the person that needed to do that interview. >> we only get one shot at it. and we have to be prepared that this could just be information collecting or we have to be prepared that this could be our suspect. >> reporter: so, only eight hours after his pregnant wife was murdered, seth's formal interview with dci agent thomas got under way. >> you can just call me chris, i you're free to go out of here at anytime. >> reporter: in the interview room, agent thomas was in the white shirt, back to the camera. to put seth more at ease, a deputy familiar to him sat in. it started out routinely. >> you have a job? >> currently, i work at job corps as security, but i'm actually next month coming to work here in the jail. >> reporter: seth had already given his account twice to deputies at the scene, but this would be his first time on videotape. his story begins somewhere around 5:00 a.m. >> exactly. >> i turned the shower on. i wasn't in there for more than five minutes and i heard this loud noise. >> reporter: he said he thought it might be a gunshot so he jumped out of the shower to check on lisa. he heard her moaning then made out another sound, coming from possibly the back deck. he said he grabbed his handgun from the nightstand by the bed. >> i run down the hallway and i will be honest, i had every intention of shooting whoever it was. i don't hear nothing. i run back inside. i run into the bedroom. and i said, "lisa, lisa, are you okay?" and she's not breathing. >> reporter: during the interview, seth sometimes seemed overcome by emotion. >> i couldn't do it. i couldn't [ bleep ] protect her when i'm tent fawee from her. why can't they still be alive? why? why? why couldn't i have done something to protect the woman that i loved? >> reporter: the agent asked seth what he thought had happened. >> let's go with your theory here that was an incrude -- intruder, right? i mean, is that fair to call -- >> that's the only thing i can think of. >> what do you think this person's intent was? >> i don't know. you'd have to be a complete [ bleep ] to walk into somebody's house and shoot them. >> reporter: seth then bolstered the cops' leading theory of the crime so far, that the neighbor, brian tate, had shot lisa. >> who was the first person that came to your mind? >> tate. my crazy neighbor who thinks that we're terrorists. >> reporter: seth went into detail about that juvenile tit-for-tat dispute with tate that started over a deer hide. he suspected tate tossed it over the fence so he said he responded in kind. >> i did the immature thing, which i admit, i threw it back on his property. >> reporter: the dispute escalated for several weeks and intensified with the incident in which tate claimed dog feces and rocks were thrown onto his property. that brought seth's father-in-law, deputy todd caldwell, out to tate's house for that official visit over tate's vandalism complaint. >> todd said that tate, the whole time, was sitting on his front porch and he was rubbing a loaded shotgun. >> reporter: seth said he knew the tenor of the visit because todd had filled him in later. his father-in-law also gave him a strong warning. >> "hey, if you're doing anything to his yard, knock it off. if your buddies are doing anything to his yard, knock it off. do not mess with this guy. he's off his rocker. he's going to be the next person -- >> sure. >> to shoot a cop." >> and i said, "i'm not messing with him. i'll make sure nobody else is." >> reporter: the murder weapon hadn't been found so the state agent asked seth about the firearms he kept in the trailer. maybe one of those had been used. >> do you have any guns that are missing at your house? >> i haven't looked. >> if one of those guns is used in the homicide, we want to know where it's at. >> don't you agree? >> oh, yeah. >> so i just ask him to write down the guns that are in his house. and he writes them all down. >> reporter: inevitably, the agent turned to the sharp-edged, intrusive questions that all husbands with a murdered wife have to answer. wannabe cop that he was, seth knew very well what was coming. >> we're going to ask you some tough things, okay? >> that's fine. >> okay. >> i know i'm, obviously, probably number one right now. >> let's talk about people that are in your lives and lisa's lives. was there any extramarital affairs? >> no. >> reporter: seth didn't there was no other women. but out at the trailer, quite unexpectedly, someone was about to put the lie to that rosy marital picture. a good friend of seth's named colton had walked up to the crime scene tape at the drive. he told the deputies and agents there that he was looking to pick up his puppy that seth had been boarding for him. the investigators began peppering the young friend for info about seth and lisa. a detail that tumbled out surprised them. what was the story you told them colton? >> i told them that seth had a trac phone. >> so kind of a secret phone? >> yeah. and he had been talking to a girl. >> reporter: the investigators had no idea where this would lead, but the unexpected revelation that there might be a girlfriend in the mix meant that they had to get on the horn chair, but he could walk at any moment. >> coming up -- more about seth's secret phone. seems it wasn't just for talking. >> did he tell you, "she sent me some topless pictures"? >> yes. >> did you see them? >> yes. the mercedes-benz winter event is back. lease the e300 sedan for $569 a month at your local mercedes-benz dealer. mercedes-benz. the best or nothing. ♪ ♪ you are a city city wall, city wall ♪ ♪ ♪ she could be dancing down a hall, dancing down a hall ♪ ♪ we're turning heads, oh yeah and nothing can stop us now ♪ daily hair damagen stop before it happens ...with these roses. one is treated with dove. both are exposed to damaging heat. the rose without dove is dry and brittle. dove deeply nourishes and stops 90% of daily hair damage before it happens. packing to the last minute. time to break these bad boys out no i have a couple of things to wash we got this- come on. even on quick cycle, tide pods cleans great let's go did you just get up uh-huh it's got to be tide directv has been rated number one in customer satisfaction over cable for 17 years running. but some people still like cable. just like some people like pre-shaken sodas. having their seat kicked on an airplane. being rammed by a shopping cart. sitting in gum. and walking into a glass door. but for everyone else, there's directv. for #1 rated customer satisfaction over cable, switch to directv and get a $200 reward card. call 1-800-directv. >> reporter: seth techel had gone downtown voluntarily, but now his interview had dragged on for a couple of hours. his father grew concerned, so he called in a lawyer, who said he would bring the questioning to a halt. >> and we had called the sheriff's office and said, "we have a lawyer waiting to go see seth." >> reporter: but inside the sheriff's interview room seth kept talking away. he was oblivious to the fact that the interrogator confronting him was getting realtime bulletins from the crime scene. >> i got a text. >> reporter: the text was from a fellow agent at the scene who had spoken to seth's best friend, the guy with the puppy. >> reporter: and this person had told him a story about a girl named rachel. >> reporter: but agent thomas held his fire at this point, in part because his information was still limite the husband -- father-to-be, who had answered an emphatic "no" to the question about an affair, then made an admission, perhaps a preemptive strike. >> there was a female from work that i was texting. >> reporter: he said her name was rachel mcfarland, but seth immediately downplayed her importance. he said even lisa knew about her. >> but it wasn't seeing her. it wasn't anything. it was just hey, how was your day type of thing. >> would it be considered sexting? >> no, no. none of that. >> what are you wearing? >> no, there wasn't any of that. lisa found out. everything was kosher. i stopped talking, you know, we got over it. >> we have to be honest about her, okay? is there anything that you haven't told us yet? >> no. everything is going to add up the way i just told you. >> rachel's dna won't be maybe on your clothes or? >> i never had sexual -- sex with her. no, nothing oral, nothing like that. her. >> reporter: by now, seth's father and attorney had arrived and were trying desperately to end the interview. but it was after hours and the outside door was locked. >> bang, bang, bang on the door, doug. is that you? >> that's me. that's me. >> they wouldn't stop. >> they -- >> they didn't come out. >> didn't stop. >> reporter: they didn't have to. remember, seth was advised by agent thomas that he was free to leave time -- anytime. everything was legal. lead agent birmingham, watching seth on a monitor, simply ignored the commotion outside. >> i did get information that they were wanting to get in and wanting to come in and tell seth to stop. >> reporter: which would shut you guys right down. >> seth is an adult. and he has the sole obligation to invoke his right to remain silent or his right to an attorney. and no one stopped him from doing that. >> reporter: so thomas kept asking questions, and seth kept answering them. >> have you ever lied to lisa about rachel? >> no. that was that. >> reporter: meanwhile, both dci agents birmingham and thomas had now learned more complete details from the scene from seth's best friend, the guy with the puppy. the friend, colton, had explained that seth was using his special trac phone as a steamy hotline. >> i know they were exchanging photos. >> reporter: did he tell you, "she sent me some topless pictures?" >> yes. >> reporter: did you see them? >> yes. >> reporter: armed with this information, agent thomas decided to show his cards and see what happened. >> we've talked to colton. did colton know about you texting rachel? >> mm-hmm. >> did you tell him about it? >> yeah. >> this is an ongoing investigation, and it's up to you to be honest. >> there's obviously more to this rachel thing. she was under the impression that lisa was going to be packing her stuff up and leaving. >> when? >> last night, today. >> reporter: he said he'd talked to rachel about him divorcing lisa as recently as the night before at work. >> she just asked if i was going to go through with it and i said, yeah. i mean, i shouldn't have lied, obviously. liked rachel's attention but said he really was just stringing her along. >> we were having a baby. i wasn't going to leave her. i couldn't leave. >> reporter: lying to rachel was wrong, he said. but he claimed that lying earlier in the interview was a way to spare his grieving father-in-law, todd caldwell, the embarrassment. >> this is something i didn't want todd to find out. >> reporter: the interview had been going on close to four hours now, and agent birmingham was well aware that seth's father and a lawyer wanted to shut it down. agent thomas then took a break, leaving seth inside the room to stew. he met with birmingham, and they decided he had to go nuclear. >> be confrontational, because the clock is ticking. >> and if we're ever gonna be tough, now is the time. >> now is the time. >> here's the deal, okay? the facts right now, these case facts, show us you're responsible for killing your wife. >> no, no. i'm not, no. i can't kill my wife. i can't do it. what facts do you have that i killed her? >> listen, i've seen rachel, okay? i know what guys see when they see her because i see the same thing. okay? >> i'm telling you, if i wanted to be with rachel, i would get a divorce. i would not [ bleep ] kill my wife over something that small. you know what? right now i guess i don't give a [ bleep ] what happens to me, okay? i know what happened, i know what you're trying to do. >> what am i trying to do? >> you're trying to get me upset and it's working. congratulations. >> reporter: upset at this hostile line of questioning, seth said he'd had enough. got up and strangely shook thomas' hand. >> appreciate it. >> reporter: and then he walked out. in the end, what did the investigators have? that seth lied about sex, but was it even that? all he admitted to was making insisted, over and over again, that he did not kill lisa. even agent thomas expressed disappointment with the outcome of the marathon interview, nearly five hours long. >> you felt you'd come out of a 15 round fight? >> it was exhausting. felt somewhat like a failure, in some regards. >> why? >> we didn't get the full confession. >> reporter: maybe that's because seth didn't do it. agent thomas just didn't know. but the women in the caldwell family, without knowing any of seth's admissions about rachel, believed with 100% certainty that seth did not kill lisa. especially lisa's sister and seth's great friend, presley. >> i was never thinking that seth did it. >> reporter: only todd caldwell was no longer a true believer. the cop in him questioned why seth needed to lawyer up. his own investigative instincts also kicked in, though he'd asked his fellow deputies not to tell him anything until they and late on day one of the investigation, they weren't even close. >> i would say at 10:00 on saturday night may 26th neither seth nor brian tate were completely eliminated as suspects. >> reporter: at that time, investigators were meeting at the sheriff's department command center to take stock. they knew they had a husband with a possible girlfriend and a maybe crazy neighbor with a vendetta. but they also learned by that night there was a missing shotgun. what did it all mean? coming up -- one piece of the puzzle falls into place. >> reporter: boy, that was a huge development in that case? >> it was. >> and then, another round of heartbreak for lisa's family. >> reporter: this has got to be just more than your brain can absorb. >> definitely. >> when "dateline" continues. ...from far away. but they harryonly see his wrinkles. if only harry used some... ...bounce, to dry. he would be a less wrinkly, winning guy. this holiday season... give the gift of effortlessly smooth feet... from amope. amope pedi perfect with diamond crystals. removes rough, hard skin... effortlessly... for touchably smooth feet. the perfect gift... for that special someone on your list. returning to our story, lisa techel, pregnant with her first child, has been killed by a shotgun blast. investigators have quickly zeroed in on two suspects -- lisa's husband, who may have been involved with another woman, and a neighbor who had an ongoing beef with the couple. but lisa's grieving family is only at the beginning of a long legal odyssey, starting with a bombshell arrest and leading up to an explosive secret revealed from beyond the grave. here again, dennis murphy. >> reporter: it was sunday, the morning after lisa techel had been shot to death. but it wasn't a day of rest for the tech arrangements. one of the saddest words in the language is, arrangements. we have to make arrangements. that must have been unreal. >> yeah. >> i don't remember it. >> reporter: grief-stricken, todd decided to stay home by himself while the rest of his family and the techels met in a park. seth was there, but under instructions from his lawyer not to speak about the case. he shared an emotional moment with lisa's sisters and her mother, tracy. >> the first thing -- seth grabbed the girls and hugged the girls and said, "they think i did it." we all hugged seth, you know, told him we loved him. >> reporter: when investigators finished their forensic work inside the trailer, tracy, seth, and his parents went out there to retrieve some of lisa's things. >> it was very tough. i was just amazed the way it looked. >> crime scene techs had been all over it, hadn't they? >> all over it. i guess i went into dad mode and tried to protect seth a little bit. and i wanted to cover up the bed. >> reporter: what was your thinking there? the blood. >> how was your boy dealing with all this in these hours after? >> i think he was just shocked. >> reporter: that sunday wasn't a day of rest for the men and women trying to solve the crime either. investigators were focusing on the murder weapon and were working a lead on a 12-gauge mossberg shotgun. it belonged to seth's friend, lucas howell, who'd been rooming with seth and lisa and had just moved out. we showed lucas this photograph taken of seth at his home. if you look in the upper right-hand corner, lucas, it's the gun rack. is your mossberg in that rack? >> yes, it's the middle one. >> reporter: lucas talked to deputies about the gun on the day of the murder. >> i told them that i hadn't took it with me and it should be there. >> reporter: but his 12-gauge wasn't there when crime scene techs scoured the trailer. and cops knew another place it wasn't. on the list of guns kept at the house that seth had written out for the dci agent. investigators felt certain the mossberg was used to kill lisa, but a big question remained. >> where is it? that's where is the gun? >> reporter: that same sunday morning, a team began searching the big, beautiful piece of property where seth and lisa were starting married life and preparing to raise a family. deputy marty wonderlin, working his first-ever homicide case, was back at the scene. >> not too long into the sunday morning search, over here by this big old tree, what do you hear? >> i hear, "we've got it. you know, shotgun here." they were going nuts. >> reporter: there was the mossberg in the tall grass, about 20 yards from the back door of the trailer. >> boy, that was a huge development in that case. >> it was. i think everyone's, you know, mood doubled or tripled when they found that gun. >> reporter: ballistics would later match the mossberg with the slug that killed the pregnant lisa. investigators could fill in one big box on their checklist -- murder weapon. next, they worked on possible motives. was it a neighbor with a vendetta or a husband lusting after another woman? state agent birmingham and deputy phillipde a talk with seth's work friend, rachel. >> we interviewed her on tuesday, may 29th. >> there's no tricks here, someone has lost their life. actually two people have lost their life. >> reporter: over the course of two hours, birmingham and phillips peeled back the layers of rachel's relationship with seth. >> they were having, you know, kind of an ongoing relationship. there are sexually explicit text messages. there are pictures, sexually explicit pictures, sent back and forth. >> he kissed me, but it never led into anything else. he just used to tell me i love you. that's about it. >> reporter: it sounds like they were making out rather than having sex. >> yeah, yes. that's correct. >> he always used to tell me how pretty i was and how he'd like to be with me. but i always made it clear that he is married and has a wife, and he's having a baby and i don't wreck families. >> reporter: rachel told the investigators the seth she knew couldn't be a murderer. >> would it surprise youhe did this? >> honestly? yes, it would. >> reporter: but seth was a suspect, and if he did fire that shotgun blast, that would place rachel at the heart of a murderous love triangle. >> i think that's why i feel so guilty, because i don't want it to be because of me. >> reporter: the next day, deputies phillips and wonderlin were back at the neighbor brian tate's house. >> deputy wonderlin and myself deputy phillips are pulling up here at the tate residence to re-interview mr. tate. >> reporter: this time, they asked him point blank about the murder of his neighbor. >> we're just trying to figure this all out, you know. did you have anything to do with lisa's death? >> no, i didn't. >> reporter: tate stuck to his alibi. home and asleep after taking his medication. lead agent birmingham thought he was telling the truth and crossed brian tate off his suspect list. so you only had one suspect at this point. >> yeah, one suspect and only one suspect. >> reporter: that evening, lisa's loved ones gathered at a funeral home for the visitation. the turnout was impressive and included many of todd's friends in the sheriff's department. your fellow officers are there as they would be, you know, they want to show condolences, respect. >> right. >> reporter: the mood inside was somber and uneasy. the caldwells gathered near lisa's coffin. the techels stayed in the back of the room. seth was there. his sister-in-law presley will never forget what happened next. >> he actually came up to me, kind of in the middle of it, he gave me a big ole hug and he said, you will always be my little sister and i love you. and i was like, i love you back. >> reporter: when the last visitor was gone, only the two families remained, still at opposite ends of the room. >> then i saw the two dci agents come in and sit down behind me, a couple rows behind seth and i. i said, "is this a personal visit or professional --" >> reporter: is this condolences or something else? >> yeah, and he said, "it's professional." >> reporter: marty wonderlin was there. >> we asked seth to, you know, come outside. thought. >> reporter: and when they were outside, deputy wonderlin carried out his orders, he arrested his friend seth techel. a fellow deputy put the cuffs on him. they were lisa's cuffs, the ones she'd used as a reserve deputy. so this has got to be just more than your brain can absorb. >> definitely, yeah. >> reporter: little sister, "i'll always love you," and now, he's going downtown. he's about to be charged. >> yep. i couldn't understand it. we wouldn't ever dream or ever understand that it could be him. >> reporter: seth's dream was to drive a sheriff's car as a deputy. but now the wannabe cop was cuffed, riding in the back seat, and about to be charged with the murder of his wife. >> coming up -- seth techel goes on trial. but before it even starts, the prosecution suffers a major blow. >> bad for us. good for them. it's great for them. >> and then, a clue you haven't heard about could change everything. >> i believe it to be the most compelling piece of evidence in the whole case. 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maybe? you can leave worry behind when liberty stands with you™. liberty stands with you™. liberty mutual insurance. >> reporter: for lisa techel's family, it had been a heartbreaking, relentless week. thursday didn't promise to be any better. lisa's funeral was held at the first lutheran church in ottumwa. seven months earlier, todd caldwell was at the very same church, walking his daughter down the aisle on her wedding day. now, he'd return to lay her to rest. lisa was buried in her jailer's uniform. a special detail of officers served as pallbearers. law enforcement had come out to honor one of itswn >> lisa would have thought, you know, this is all for me? i was so proud. >> i should've been able to be there and -- and watch her become a mom. she was just a joy. >> mothers shouldn't bury daughters. >> never. never. >> reporter: after the funeral, the caldwell and techel families turned their attention to the upcoming murder trial of seth techel. lawyers started to plot strategy, with the neighbor, brian tate expected to be right in the thick of it. tate's sister cheri says he never could shake the feeling that the authorities would come after him. >> he still feels like they're saying he's a murderer. brian had even seen in the paper that they were calling him a crazy deranged neighbor. it just devastated him. >> reporter: that summer, brian tate tumbled into a downward spiral and never recovered. he died in september 2012, just four months after lisa's murder. the coroner would think it was heart. >> yes. >> what's the family think it was? >> we think it was heart. a broken heart. >> reporter: and now prosecutors andy prosser and scott brown -- from the state's attorney general's office -- worried that deceased neighborhood did it. their plan had been to call tate as a witness. >> on the theory that the devil you know is always better than the devil you don't, we wanted the jury to see mr. tate. >> reporter: but now with a trial date approaching, prosecutors had lost a key witness. >> bad for us. good for them. it's great for them. >> reporter: the long-awaited murder trial of seth techel was in hometown ottumwa. >> ready for the jury, gentlemen? >> february 2013, can you see yourself going into the courthouse? >> yeah, i remember. >> what do you two say to one another? >> we got to stay strong. >> reporter: the caldwells never wanted to believe seth killed lisa. but, heading into trial, they were all now convinced that he did, even presley, once his staunchest supporter. >> there's really no other explanation for what has happened. >> when you left the techel residence, who was there? >> reporter: two prominent families, the caldwells and techels, once close in-laws, were now fiercely divided, camped out on opposite sides of the courtroom. seth had pleaded not guilty. >> i was like, "just look at me, like, i want to see kind of in your eyes, how you're doing," but he doesn't look at you. >> she was like my best friend. >> reporter: prosecutors called to the stand their emotional trump card. todd caldwell remembered his lisa. >> everyone would tell me how much lisa and i are alike, and i would just tell everybody that she's the best parts of me. >> reporter: the prosecution had the burden of proving the charges, first-degree murder and nonconsensual termination of a pregnancy. what did you think your strongest fact was going forward, strongest part of your story for a jury? >> probably the most important single piece of evidence was the shotgun. >> reporter: ballistics showed this mossberg 12-gauge was the murder weapon, a firearm that seth kept inside his house, and only he had access to it that morning, prosecutors argued. >> no murderer who wants to kill lisa techel comes to the murder scene without the murder weapon. >> we argued the impossibility of his story. some unknown assailant breaks into his house and kills the wife that he says he's going to leave. >> tyler batterson is our next witness. >> reporter: prosecutors called one of seth's young friends to show the jury, they said, just how deceptive and manipulative seth was. this witness was one of the boys, it turned out, behind all the vandalism across the fence. he testified he was just following seth's orders. >> he told us to go mess with his neighbor tate. >> how were you going to mess with him? >> fill five gallon buckets full of dog manure and go dump them on his property. >> reporter: remember, seth had assured his father-in-law -- and the state agent who interviewed him -- the exact opposite. >> and i said, "i'm not messing with him. i'll make sure nobody else is." >> reporter: looking back, that place, fixing the idea in his mind that his kids' neighbor was a deranged, maybe dangerous crank. >> i'm going by what seth had told me about him. >> reporter: as for tate's complaint calls with the deputies, as captured on dashcam video, it became evidence for the prosecution. >> we were hopeful that the jury would see brian tate as we saw him. >> reporter: and they saw him as an eccentric, but harmless man. certainly not a killer. then, at last, it was time for the state's star witness, rachel mcfarland, the other woman, to show up and tell her story. did you need the jury to like her? >> we needed the jury to believe her. >> reporter: rachel testified her relationship with seth started heating up in december, 2011, which was two months after seth got married. >> it became more sexual, asking me to send pictures. or, i don't know, just showing >> reporter: on may 20th, 2012, seth and rachel met at a nature preserve, where they took this selfie to remember their time together. >> i mean he kissed me, touched me. he said that we had everything in common and that he had tried working things out with lisa and they just weren't working and i was exactly what he wanted. >> reporter: she said seth repeatedly told her he was going to divorce his wife. >> did he say he loved you? >> yes. >> reporter: but rachel was hedging her bets. she told seth she was also interested in a co-worker named brandon, who just happened to call her during her tryst with seth in the park. >> he just started getting really jealous. >> and so on the 20th when he learned that you were communicating with brandon, he said what? >> just give me two more weeks. >> did you ask him what he meant just give me two more weeks? >> yes, and he just repeated the same statement. >> reporter: six days later, lisa was murdered in her own bed. >> and here we have a motive that we can undend the whole relationship with rachel was evidence that was like a countdown to lisa techel's death. >> reporter: but defense attorney steve gardner countered, arguing the motive of an affair falls flat without the essential element, sex. >> seth techel was being accused of murdering his wife for an affair that he was hoping to someday have. >> you never had intercourse with him. >> no. >> you've never had oral sex with him. >> no. >> never had your clothes off. >> no. >> and you kissed a few times. >> yes. >> is that a fair assessment of the extent of your romantic relationship with mr. techel? >> yes. >> reporter: the defense also didn't accept the state's take on the neighbor as a harmless eccentric. >> the most compelling evidence as to how this occurred involved the neighbor, mr. tate. he was mentally ill. >> i'm done talking to you. >> reporter: and according to the defense, dangerous too. the defense then hammered home the portrayal of the unpredictable neighbor by using todd's own complaint summary from that day. you're in the awkward situation of being their best witness. >> right. >> you believed he could become a danger. anyone who should respond to that residence again should use extreme caution. >> that is correct, i did. >> reporter: the defense theorized that tate entered the trailer through an unlocked door and shot lisa for revenge. the key defense evidence that suggested an intruder was a stray peanut butter and jelly sandwich in a baggie left on the back deck. >> there was a sandwich that would not have been there the night before that was there. >> reporter: critters should have devoured it, he argued. he told the jury it must have been the killer's snack. >> i believe it to be the most compelling piece of evidence in the whole case. >> reporter: it was now up to a jury to decide. but it wouldn't be easy. >> coming up -- in the jury room, deliberations and drama. >> he started pounding on the door saying that he wanted out of there. and we were in tears. >> when "dateline" continues. sometimes a cough gets in the way of a good night's sleep. that's when he needs vicks vaporub. proven cough medicine. with 8 hours of vapors. so he can sleep. vicks vaporub. goodnight coughs. battery this holiday? 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(screaming) or, you could just trust duracell. ♪ it's beginning to look a lot like christmas ♪ >> reporter: back in the deliberation room, wrangling jurors in the seth techel murder trial were driving the case into a ditch. they stay out and they stay out and they stay out. what are the prosecutors telling you, todd? >> that there are some that are guilty and there's some that are not guilty, and they're just not agreein'. and i'm starting to get worried at that point. >> reporter: micah sheheen was on the jury. she said one holdout juror in particular was responsible for the stalemate. >> he started pounding on the door saying that he wanted out of there. and we were in tears. a lot of us because we knew that we were up against a wall, that nothing else could be do w three full days of deliberations, the seth techel murder trial came to a sudden conclusion today. >> reporter: it was all over. >> the motion for a mistrial is hereby granted. >> reporter: the judge declared a mistrial because of a hung jury. hung jury? punch to the gut, andy? you ever have one? >> well, i never had one in almost 30 years. >> reporter: prosecutors immediately decided to retry the case. the vote had been 10 to 2 for conviction. >> of course we're disappointed in what happened. >> reporter: the caldwells had lost a daughter and sister and, now, they couldn't even get the closure they desperately wanted. and they'd have to do it all over again. >> it's hard to know that you're going to have to endure another one. >> reporter: a trial date was set for seven months later, october 2013. and trial number two would be heard in a new courthouse. there'd been a change of venue to the town of mt. pleasant. making it even tougher on the caldwells, the daily treks to court, lives disrupted. the new courtroom had a distinctive layout that put the caldwell family directly behind the defendant. >> he's literally sitting right in front of me like you are. >> reporter: which only made it more frustrating for presley who was still trying for any kind of connection to someone she once loved like a brother. >> i'm just staring at him, like, just glance at me. do something. and he doesn't. >> reporter: and even more painful for the family was having to sit through again all that heartbreaking testimony and raw crime scene photos of their lisa and the unborn baby girl. >> reporter: other than the change of venue, seth techel's second murder trial played out as a carbon copy of the first. same lawyers, same judge, same arguments. a replay of two opposing theories -- brian tate, the other suspect, versus seth techel, the husband with the other woman. rachel mcfarland was, again, the prosecution'ar >> here on may 4th of 2012, he sent you a message with a picture of his own smiling face saying, miss you bella. >> mm-hmm. >> is that a term of endearment that he called you, his bella? >> yes, yes. >> you sent him a picture of you in either a bikini or your bra and underwear. is that right? >> yes. >> and then he says, "well, wish me luck. i love you" at 10:51 p.m. on may 24 of 2012. what was he asking you to wish him well with? >> i believe that he was going to tell her that he wanted a divorce. >> reporter: two days later, lisa was dead. by now, her family had hardened opinions about rachel. >> i don't think too highly of her. i felt like she destroyed my sister's marriage and her life. >> reporter: todd, rachel, huh? >> actually, i'm maybe not the most popular view. i blame her for what part she had to play with seth, but i victim as well. >> reporter: the defense offered the jury the same bogeyman as before. >> the defense went even harder at brian tate than they had the first time around. >> he could quickly become volatile and agitated. >> reporter: this time, the defense, over strenuous prosecution objections, got tate's psychiatrist to testify. he'd treated him near the end of his life in a hospital mental health unit. >> when you first saw him, did you find him to be paranoid delusional? >> yes, sir. >> and was there a general topic of delusion of which he was paranoid? >> he seemed to make reference that there were some governmental conspiracies affecting him. >> reporter: after three weeks of trial, a second jury had seth techel's fate in its hands. and that's when things got deja vu all over again. the judge read a note from the foreman. >> we're not going to reach a verdict. what's next? >> reporter todd, it's happening again. >> yep. i' months worth of trials and we're right back to the beginning. >> reporter: but the judge wasn't ready to give up. he told the jurors to keep trying. emotions in the open courtroom were raw, especially on the caldwell side. the jury couldn't help but hear it. >> presley and i were crying. we weren't crying uncontrollably or anything. but you could hear us sniffling a little. >> reporter: as the jury filed out, defense attorney steve gardner rose to scold the spectators. stop the over-the-top outbursts, he said, or he'd demand a mistrial in fairness to his client. >> i do not desire this jury to be influenced by the public. >> reporter: now, it was the prosecutors turn to seethe. >> the defense is making this speech about the caldwell family trying to somehow influence the jury, which we thought was ludicrous. i squeezed andy's arm and i said, i'll take this. >> to stand up here and suggest that anyone in the courtroom is intentionally influence the jury is absolute nonsense. >> reporter: the courtroom started to settle down and clear. but seth remained at the defense table, his former father-in-law coiled behind him, ready to pounce. >> i was just praying, "please just let me stand here. >> reporter: for more than a minute, glaring, burning a hole in seth's back. if looks could kill. >> there's just kind of an urge to move forward. >> reporter: to jump the rail? >> yeah. god, please don't make me do that. just let me stand. >> what were you doing in your mind? >> i don't really want to even think of what i was doing in my mind, but i was -- i was wanting to do something. >> reporter: two hours later, the jurors returned. but nothing had changed. >> a mistrial is declared. >> reporter: unbelievable. veteran prosecutors who'd never had a hung jury before, were now zero for two. again, the state didn't hesitate. seth techel would go on trial for a third time. >> our intent is to retry it. that was an easy decision to make. >> reporter: even though the jury's vote was again in favor of conviction, this time nine to three, lisa's family was starting to have its doubts. >> is there something that i'm just overlooking? like did he not do it? is there something that they just see and they're like -- he's not guilty? >> reporter: but just when they thought they couldn't suffer any more heartbreak, the caldwells would be devastated by new findings by a brand-new defense team. >> i heard it about a week before the trial and it -- just like somebody hit me in the stomach. >> coming up -- the defense comes out swinging. >> we chose to focus on the sloppy work done by the law enforcement. there was absolutely no dna, fingerprint, confession. nope, you blinked. i didn't blink. give thanks for the healthy kids in your life. visit stjude.org or shop where you see the st. jude logo. i could do this for a hundred years. this guy's...is guy? been through a lot. dogs bring out the good in us. pedigree brings out the good in them. feed the good. fredget in, fred!thing for his daughter. even if it means being the back half of a unicorn. the front half washed his shirt with gain flings! and that smell puts the giddy in giddy up. that's because one gain flings pac has more freshness than a whole bottle of the other guy. gain. seriously good scent. hair damage even before itaily happens? dove proves it is with these two delicate roses. one rose is treated with dove. when exposed to the same level of damaging heat, the difference is clear. the rose not treated with dove is dry and brittle. dove fortifies by nourishing deeply and stops 90% of daily hair damage before it happens. dove intensive repair. >> reporter: two families. two trials. and so far, no winners. but trial number three promised to be different, starting with a new defense team. >> the previous trials were not successes. and seth came dangerously close to being convicted in ea o jake feuerhelm knew that, in two trials, 19 of 24 jurors had voted to convict seth techel. they didn't like those numbers and decided to head in a different direction. >> we chose to focus on the sloppy work done by the law enforcement. there was absolutely no dna, fingerprint, confession. >> reporter: feuerhelm would argue it was a botched investigation. why would crime scene techs do tests to match the slug to the murder weapon, but never check it for fingerprints or dna that might link it to the shooter? >> did you test the bullet that was in the chamber that killed this woman? no, we forgot, or we didn't do it. >> whoops. >> whoops. >> reporter: the new defense team had a new story to tell. it was all a rush to judgment to blame seth, who'd been in jail ever since his arrest two years earlier. and there was another big strategic shift. they would soften the focus on the boogeyman of the first two trials -- brian tate. >> our conclusion was after listening to the tapes of mr. tate that he wasn't the deranged person that they tried to portray him as being. >> the way he was speaking to law enforcement that afternoon would not seem like the person that would have walked into a trailer home at 5:00 in the morning and murdered his neighbor. >> reporter: the defense attorneys made a tactical decision. since recordings of tate didn't make him look like a dangerous killer, they would not show tapes of him to the jury. and they'd roll the dice, hoping the prosecutors wouldn't either. >> the caldwells and techels had been put through the wringer for more than two years, their once close relationship had frayed. and now the third trial was pushing everyone to the brink. it was an impossible situation, but somehow todd caldwell and doug techel managed to find a moment of grace. >> i went over to him and i just said, "doug, i want you to know that i think you're a great guy. i think you're a good person." >> did you really? >> "no matter how this turns out, i just want you to know that." and he said, "i think the same thing with you, todd." and i went to shake his hand and he just hugged me and we both just hugged. >> reporter: the two fathers then returned to opposite sides of a murder trial. july 2014, for the third time, the state of iowa versus seth techel. >> counsel, you ready for the jury? >> reporter: this time in davenport, three hours from the first courthouse in ottumwa. the prosecutors once again argued that seth's story defied logic. >> he would have to be the victim of one of the largest coincidences ever known and that is he told his girlfriend that he left his wife. and a little less than 17 hours later, some unknown assailant breaks into his house and kills the wife that he is -- says he's going to leave. >> with a weapon which he hasn't brought with him. >> correct. with a weapon which he hasn't brought with him. >> i had a mossberg model 500 shotgun. >> a 12-gauge. >> yes. >> reporter: and seth, prosecutors said, had easy access to the murder weapon, the shotgun that his friend lucas kept in seth's house. >> is that the same 12-gauge mossberg shotgun that you left behind in the techel residence 2012? >> yes. >> reporter: and, the prosecutors argued, only seth had a motive. they said seth and rachel's steamy texts and cell phone photos played like a countdown to murder by seth. >> at 9:20 p.m. on the 24th, you ask him, do you really want to be with me? and he responds, "forever." >> right, yes. >> reporter: that's may 24th, two days before lisa's death, and in a follow-up text, rachel asked seth if he'd told his wife he wanted a divorce yet. >> and he responds, "well, we talked. i told her i wasn't happy, she got mad, then sad, then i slept on the couch. so hello, mrs. resuscitator. >> correct. >> reporter: rachel told the jury that she and co-workers nicknamed seth "mr. resuscitator" because he was a volunteer firefighter who often bragged about his life-saving cpr heroics. mr. resuscitator and you were going to be mrs. resuscitator. >> yeah. >> reporter: then to drive home their contention that seth chose murder over divorce, prosecutors called a co-worker who'd been a confidante of seth's. >> i just expressed he just needed to either end his marriage or end it with rachel. >> and in saying that he should end his marriage with lisa techel, did he make any comment concerning child support? >> he asked me if i wanted to pay his child support. >> reporter: and then the witness recalled another remark seth made about lisa. >> he stated that it would be better off if she was in a car wreck and died. >> reporter: prosecutors hoped their third time would be the charm. but, the new defense attorneys would come at them with everything they had and that included explosive new evidence. this time, it was about lisa. >> coming up -- >> reporter: you found out the story told by the phone? that there was this guy -- co-worker? >> right. >> was there another man in lisa's life? plus motorcycle, boat and rv insurance! geico's got you covered! like a blanket! houston? you seeing this? geico. expect great savings and a whole lot more. so find a venus smooth that contours to curves, the smoother the skin, the more comfortable you are in it. flexes for comfort, and has a disposable made for you. skin smoothing venus razors. i used to ask if you can hear me now, but i made the smart choice hi, i'm paul. and switched to sprint. these days all networks are great. so why would anyone pay twice as much with verizon. now when you switch you'll get 4 lines of unlimited for $25 a month with the 5th line free. 5 lines for only $100 a month. that's 50% off the unlimited rates of the other guys. it's the best price for unlimited. (vo) don't let a 1% difference cost you twice as much. plus, switch and get 50% off samsung's newest phones. think about what you can do for people with hearing loss, >> reporter: from the day lisa techel was murdered, brian tate had been targeted as a suspect. >> go get him. go get him. now. >> reporter: and he'd been exploited by seth's defense ever since. >> the question that you will have to consider is whether or not the state has proven that seth techel did it. >> reporter: new defense attorneys roger owens and jake feuerhelm had a completely different strategy. they barely mentioned tate's name. rachel, offered as seth's motive for murder in earlier trials, was also minimized this time. >> good afternoon, miss mcfarland. >> hi. >> reporter: in cross-examination, rachel was on the stand for a scant seven minutes. tick tock, there's the message on thursday. mr. and mrs. resuscitator, blue skies ahead. we're a couple. what do you do with something like that? >> i tried to be as straightforward as i could with the jury. who in the world is going to murder their wife to facilitate a relationship that hasn't even turned sexual? >> you're not having any sex with this man, right? >> correct. >> and the only time you'd actually seen him in person, in your whole entire life, outside of work, was four or five times. >> correct. >> i have no further questions. >> what we wanted the jury to think about her is that you're going to shoot your wife for this? >> reporter: attorneys feuerhelm and owens then went on the attack, characterizing the work of investigators as woefully shoddy. >> the ayes have them -- inconsistent, incompetent, incomplete. >> reporter: the new defense this state criminalist had to admit they did not test for gunshot residue on seth techel. >> how many times do you think you testified in criminal trials that gunshot residue was evidence of a crime? >> a lot. >> but in this case, no, we can't argue it because we don't have it. >> yeah, exactly. we'll never know. >> never know. >> reporter: and the defense said it was even more shocking that this state expert had to make a similar admission about the fatal shotgun shell. >> this is the shell that killed lisa techel. >> yes. >> the very shell that killed this woman was never examined by the state. they just said, we forgot to do it. >> reporter: but the centerpiece of the defense case against the cops was something else they didn't do. they years before, that they never really paid attention to lisa. the new defense team would change all that, starting with her cell phone and the secrets it held. you found out the story told by the phone? that there was this guy -- co-worker? >> right. >> reporter: it was a bombshell. lisa was having an affair with a fellow jailer. >> lisa's lover was a married man, a father of four. >> reporter: and this is not making out in the back of the car? >> no. he thought he could even be the father of her -- of the child. he thought that. >> reporter: so they called lisa's lover, jason tinnes, to the stand. >> back in may 2012, did you know lisa techel? >> yes, i did. >> reporter: jason testified that the affair started before lisa married seth and ended just weeks before her murder. >> mr. tinnes, at some point did your relationship with lisa techel become sexual? >> yes, it did. >> now when we talk about a sexual relationship we're t sexual intercourse correct? >> yes, sir. >> reporter: for lisa's father, the revelation that his daughter had a lover was the cruelest blow yet. >> the first emotion i had is why, why lisa. you know? and my second thought is i don't want to tell amy because i know she's not going to be happy. >> reporter: does it taint your memory at all? >> really, what it did for me more than anything is, i have so many more questions that i'll never get the chance to ask her. i mean, i love lisa and she was a human being and she made mistakes. >> reporter: the graphic testimony about lisa's affair, and how police overlooked it, fit perfectly with the defense's theme of a botched investigation and a rush to judgment against seth. >> here's a legitimate suspect that should have been investigated. >> reporter: investigators never spoke to jason while they were building their case against seth. prosecutors finally contacted him just days before the third trial started. >> so between may of 2012 and you didn't talk to anyone about this at all? >> no, sir. >> reporter: but prosecutors fought back. jason had an alibi witness, his wife. they called her to the stand. >> do you have any memory miss tinnes as to the whereabouts of your husband on may 26, 2012 at approximately 5:00 a.m.? >> he was sleeping with me at our house. >> reporter: and dna testing on jason done right before trial also proved he was not the father of lisa's baby. but the defense still believed that raising the story of lisa's affair and how police never uncovered it would give jurors reasonable doubt about the entire investigation. because this is the big part of oi your case in trial three. jurors, you're seeing some really shabby police work here in terms of investigation? >> it fell right into our theme, to our theory of the case. >> reporter: testimony in the third trial, streamlined by both sides, took half the time the that was another part of the new defense team's revised strategy. there'd already been five holdout jurors in the previous two trials. now todd caldwell worried that the new defense team had produced a cloud of even more reasonable doubt. >> you kind of think, okay, if i was on this side, that's kind of how i would have handled it. they're doing a pretty good job. and i'm convinced it's going to be another hung jury. why wouldn't it be? >> coming up -- todd, and just about everyone else, are in for a surprise. >> has this jury reached a verdict? so i get a better clean. i mean, i give away water for free. i'm not about to pay for it in my detergent. #1 trusted. #1 awarded try tide purclean ♪ ladies and gentleman this is a robbery. what are you doing after this? ♪ hey, l'eggo my eggo. i don't see your name on it. really? ba bam! know the rules. keep your eggo. l'eggo my eggo. okay. i wanti did my ancestrydna and where i came from. 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. der your kit now at ancestrydna.com. a whole new concept in skin say heldefense.e-tox! new absolutely ageless®... ...pre-tox day mask from aveeno®. its' powerful anti-oxidant formula... ...fights pollution and keeps skin looking younger, longer. aveeno®. >> reporter: july 24th, 2014. after two agonizing stalemates, this time things were different. as seth techel walked into the courtroom and sat down his face showed no expression, no hint of emotion. he didn't glance in any direction. not at his family, and certainly not at todd, his former father-in-law. this is the young guy you used to clap he "just take care of her. that's all i ask." >> reporter: but todd was staring directly at seth, hoping to find something, anything. now, the moment was at hand. >> has this jury reached a verdict? >> it has. >> reporter: the judge asked the court attendant to read the verdict. lisa's mother could barely contain her emotions. lisa's sister, a bundle of nerves. >> count one -- we the jury find the defendant seth andrew techel guilty of murder in the first degree. signed by the head juror. count two -- non-consensual termination of human pregnancy, guilty. >> reporter: the justice system had finally spoken for lisa and unborn zoey. and then you hear the words? what do you see? >> i hear the words guilty. and i see nothing, not one single emotion from his face. >> reporter: the jurors had taken four hrs on their way out, several reached across to shake tracy's hand. presley still had one big question. >> i would love to ask him why. there's seth before may 26, and then there's seth from may 26th on. and it's almost like i don't know who that is. >> reporter: seth's parents tried to fight back tears. >> it's heartbreaking. >> reporter: on the caldwell side, tears of joy and displays of overwhelming relief. there were hugs and more hugs, more than two years of pent-up emotions finally coming out. the caldwells then walked across the aisle. the two moms embraced, united in tragedy. >> we know this family. i know it's not doug and lorraine's fault. it's not their family's fault that any of this happened. todd searched out doug. only three years before, they were all celebrating their kids' wedding together. doug and lorraine still support their son and say he didn't do what he's now convicted of doing. do you have a whisper of doubt, either of you? >> no, sir. >> none whatsoever. i never have and i never will. >> everybody's a loser. nobody wins. but i will say this. i think lisa knows somewhere that the system that she wanted to be a part of worked. >> reporter: the caldwells and techels weren't the only ones brian tate's sister cheri had been waiting for this moment, too. >> i start crying. it wasn't tears of sorrow. it was tears of joy. they had finally gotten this s.o.b. i hope he rots in prison. >> reporter: todd still carries the burden of helping to pin the blame on tate in those awful moments after lisa's murder. >> i can never tell the family how sorry i am that they had to go through what they had to. we're going to have the last word on brian tate. this is an innocent guy that was made a victim by seth. >> all rise. >> reporter: a sentencing hearing was held in september 2014. the caldwells were given a chance to address the court, but talked directly to seth. >> you know how close lisa and i was. and you know what you took from me. out of everybody in this room, you know. >> reporter: presley, lisa's sister, walked up to take her turn. during all three trials, she'd desperately tried to make eye contact with seth. >> seth was my best friend, my brother, who i loved so much. >> reporter: now, she finally got what she wanted. as she spoke, she looked straight at him. and for the first time seth stared right back at her. >> i'm going to leave you with one final thought, that i'm no longer your sister and i no longer love you. >> reporter: and then the judge handed down the sentence. life in prison with no possibility of parole. when it was finally all over, todd went to the cemetery for a private moment with his oldest daughter. >> i went out there and i just told her that we did it and she could be proud of everybody. >> reporter: todd's been back many times since. lisa's grave is a special, deeply personal place for him. he designed her headstone. what are the figures in it, todd? >> the first thing i would do when i started like sketching it is, i would just draw a heart out. for some reason in my head, it should be in the shape of a heart. the second thing i would put in there is a mother holding a baby. and lisa and i had this thing that we would say to each other. we texted to each other and everything. it's from, "the notebook," movie and it's -- we've always said, "if you're a bird, i'm a bird." you know, i mean, whatever -- whew. "whatever you are, i am." so in the hair of this, i made two birds in there. by the time i got done with it, you know, we all loved it. and it's kind of just, kind of bonded like, hey, this is part of lisa now. news 4 at 11:00 starts now. >> you see it coming our way now.

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