to think that you can drop a 5,000-pound vehicle on your child and watch him die. >> reporter: tonight on "20/20," a series of bizarre and deadly freak accidents. >> 911. >> i think i need an ambulance. >> reporter: a beloved son crushed to death under his pickup truck. >> the truck fell on my stepson. oh, my god. >> reporter: years earlier, they uncover more mystery. was it a family curse or was there a coldblooded killer at the dinner table? a lot of people have said when this guy needed money, a family member would die. tonight, we're on the ground with investigators combing for clues. you wouldn't stand a chance. >> you, you're, you're gone. >> reporter: and a daring trap, when a new wife is terrified she could be next.

the two of them are sitting there at this table. >> i asked you if you pushed the truck, and you said yes. >> reporter: tonight, the "20/20" exclusive. >> you're that close, man. you're close. come on. let it out. >> reporter: the family member who now says, i know what you did. >> here now, david muir. >> one family will never be together again. a beloved son gone, crushed under a $5,000-pound truck. and when investigators start digging, a shocking discovery. was there a deadly pattern after all? and tonight, a exclusive development. the daughter that says, i know what you did. and she has authorities in a

second state listening, too. >> reporter: it was a cold november in upstate new york, those autumn leaves vanishing in the wind and a young father about to suddenly vanish too. it wasn't unusual to find 23-year-old levi karlsen tinkering away in the garage under a pickup truck. >> he was very good working on cars. he's very mechanical. >> reporter: and on one of those crisp fall days back in november of 2008, that's exactly where his father, karl, and stepmother, cindy, found their beloved son. only this time, levi wasn't working under the truck. he was trapped under it. and this was their desperate plea for help. >> 911. >> i think i need an ambulance. >> what's going on? >> the truck fell on my stepson. >> the truck fell on your stepson? >> we just got home, and i don't think he's alive. >> reporter: levi stood little chance against the three tons of metal. that pickup truck that had been propped up had come crashing down. >> karl, they wanna start cpr. do you know cpr? >> his chest is crushed. >> his chest is crushed. >> his chest is crushed? >> oh, my god. i don't know how long he's been in there. we've been gone since noon.

>> okay. >> oh, my god. >> reporter: you can hear the cries on the 911 tape. an unthinkable tragedy for two parents who'd just found their son. police responding to the scene. seneca county sheriff lieutenant john cleere. it was right inside this barn here? >> yes. >> reporter: at first, it didn't appear to be anything out of the ordinary. >> no. it appeared to be an accident. >> reporter: a horrible accident. >> yeah, very tragic. >> reporter: the parents were upset? >> oh, yeah. absolutely out of their minds. >> reporter: but this story would hardly end here. so many twists and turns long after that 911 call. years after that horrific accident first hit the local paper in seneca county. the gateway to the sparkling finger lakes of upstate new york. in fact, down this rambling country road from the karlsen home is seneca falls, long thought to be the setting that inspired the 1946 american classic, "it's a wonderful life."

>> yeah! hello, bedford falls! >> reporter: but piece by piece, it would soon become clear that this had not been a wonderful life for that young man found in the garage. four years after what seemed to be an accident, a bombshell call to police, a call on the tip line from a member of levi's own family, telling that investigator, follow the insurance money. so you were the one who answered the call? >> yes. >> reporter: and this investigator was soon on his way back to that family farm. do you remember the call to this day? >> oh, yeah. >> reporter: the lieutenant telling us the clues were immediate. red flag number one, they discover a brand new insurance policy for levi taken out just 17 days before he died. >> that there's this large insurance policy that was collected on over $700,000 that was taken out only 17 days before the death for the young man in the garage. >> reporter: is that typical that someone that young would have an insurance policy? >> it seems unusual that a young man in his early 20s would have one that large.

>> reporter: and then red flag number two. but who was the beneficiary? >> his father, karl. >> reporter: why would you name your father the beneficiary when you have your own children? >> i think we were asking that same question, david. >> reporter: and they were soon asking something else. just listen to red flag number three. >> reporter: you discovered a note written by levi? >> yes. >> reporter: that levi had left, saying what? >> his father was gonna be the sole executor of his estate and controlled, you know, basically dispersed the money to his kids, and that he did not wanna be resuscitated. >> reporter: when was the letter notarized? >> the day of his death. >> reporter: the very same morning. and while investigators now believed the evidence was damning, karl karlsen planned his own son's death, the whole town tried to wrap their heads around this sinister plot, a plot levi's sister suspected from the very start. >> my father is a sociopath. the only one that matters to him is him. we were just pawns in his game. >> reporter: erin's brother's

death, she insists, was cold-blooded murder. >> he didn't die instantaneously. he had time to sit there and understand what was happening to him. >> reporter: and that the killer she long suspected inside their own home, their father. for years, erin says they grew up in fear of their father. and unlike his sisters, levi stayed in that small town where they were raised. he had two young daughters of his own, but he was still under the thumb of a father who erin says he was desperate to please. >> he was basically an indentured servant to my parents. and they were, i don't know who they were, controlling everything. he wanted more than anything to just have a close relationship with our father. he was really striving for that. >> reporter: but she is convinced that as her brother tried to build that relationship, her father was crafting something else, the plan to kill his son. >> you know, to think that as a parent, you can drop a 5,000-pound vehicle on your

child and watch him die, it's absolutely unimaginable. especially as a parent myself, i just can't even begin to imagine. >> reporter: we head to the local scrapyard where levi's pickup truck was taken after that accident. his truck destroyed long ago. no one knows exactly how that pickup was jacked up, but joshua trout, who knows the family, also knows the weight of one of those trucks. >> reporter: i mean, would you go under this pickup truck? >> i would never go under a truck. i don't like going underneath trucks when they're sitting all four tires on the ground. >> reporter: investigators do believe there was a railroad jack that day holding the pickup truck up, but they're unsure if there was anything else. what they do know, that truck came crashing down. you wouldn't stand a chance. >> you, you're, you're gone. i mean, you're gone. >> reporter: and just when investigators begin asking how a father could do this, the evidence of a pattern, they say, begins to mount, that karl karlsen had cashed in on insurance claims before.

august 1986, a car fire. the cause, electrical. the insurance payout, $10,000. november 2002, a barn fire that killed three prized horses. the cause, also electrical. the insurance payout, $115,000. but investigators were also learning of the biggest bombshell. what happened to karl karlsen's first wife, levi's mother? after all of the evidence you found right here on this property, what then did you make of what happened to his first wife? >> suspicious. >> reporter: when we come back, another insurance policy, another horrific tale, almost impossible to believe. karl karlsen's second wife feared she was next and what she was willing to do to trap her husband. so you send her in through this parking lot. >> yes. >> reporter: and just, she, she has a wire on where? >> underneath her clothing. >> reporter: what she got on tape -- when we come back. has to be a great one,

and i don't compromise. ok, how about 10 gigs of data to share, unlimited talk and text, and you can choose from 2 to 10 lines. wow, sounds like a great deal. so i'm getting exactly what i want, then? appears so. now, um, i'm not too sure what to do with my arms right now 'cause this is when i usually start throwing things. oh, that's terrifying. at&t's best-ever family pricing. plans for 2-10 lines, 10 gigs of truly shareable data, starting at $130 per month. use your target debit or credit redcard for an extra 5% off our every day low prices. ♪

who's more excited about back to school sthe moms? staples? or the dads? with guaranteed low prices on colored pencils, it's definitely the dads. staples. make more happen for less. you need to see this. show 'em the curve. ♪ do you know what this means? the greater the curvature, the bigger the difference. [sci-fi tractor beam sound] ...sucked me right in... it's beautiful. gotta admit one thing...

...can't beat the view. ♪ introducing the world's first curved ultra high definition television from samsung. to roll out a perfectly flaky crust that's made from scratch. or mix vegetables with all white meat chicken and homemade gravy. but marie callender's does. just sit down and savor. marie callender's. it's time to savor. ♪ ♪

reporting from joplin, missouri --

"20/20" continues. once again, david muir, with "i know what you did." >> reporter: when lieutenant john cleere reopened the investigation into levi karlsen's death underneath that pickup truck, finding what he says is evidence his father was out for the insurance money, he never expected the dramatic turn the case was about to take all the way across the country, in a small mining town in the sierra foothills of california. while you are investigating everything that happened here, you discover the story of his ex-wife. >> yes. >> reporter: could you believe it? >> it certainly raised a lot of concerns. >> reporter: the stunning discovery. levi's mother, christina, karl karlsen's first wife, had died in a 1991 house fire. and who just happened to be the beneficiary of a $200,000 life insurance policy? her husband, karl. she'd been a vibrant, doting mother. you can see her here in home

videos holding one of her three young children, erin, levi and katie. >> she literally did everything forme. she was just an amazing woman. >> reporter: but erin claims her mother was trapped in that marriage. >> my father had a -- a very horrible temper, andt didn't take an awful lot to set him off. and my mother would take the brunt of it. she would not allow him to take it out on us. >> reporter: the sister of that first wife remembers asking her the same question over and over. >> i kept asking her, you know, "why aren't you leaving him? why aren't you leaving him?" and i almost had her convinced to leave. we were this close when the fire came through. >> reporter: it was new year's day, 1991. children were napping, christina was in the bathroom when their home suddenly lit up into a kerosene-fueled inferno. >> i remember waking up and going to my bedroom door. i saw the flames, so i woke my sister up. my father, you know, bust

through the window and, you know, got us out. never once did he look panicked or frantic or frazzled, not even confused. he was just very calm and -- "let's go." >> reporter: in the fire report, karl karlsen told investigators that just three days before that fire, he'd repaired a broken window in the bathroom by boarding it up with a piece of wood and 17 nails. that window would have been his wife, christina's, only way out. and then just a week after the fire, karl hit the road, leaving california with his three young children, returning to upstate new york to be near his family. >> we all raised our concerns that we thought the fire looked very suspicious. >> reporter: that was 18 years ago. now, two deaths, mother and son, each with a big payout for karl karlsen. was he a man cursed with family tragedies? was he murdering his own family members for money? a lot of people have said when

this guy needed money, a family member would die. >> there's definitely a pattern there. >> reporter: authorities in california begin to reinvestigate, reopening the case of karl karlsen's first wife. and who was about to help take him down? karl karlsen's second wife, cindy. and you're about to see her play a critical role in the arrest of her own husband. you find all these red flags and you decide we're gonna call the wife, cindy. and what did she say? >> the first thing she said was, "thank god you called." >> reporter: she said, "thank god?" >> yes. >> reporter: investigators say cindy karlsen feared she could be next and had moved out of their home. she was afraid. >> yeah. >> reporter: she was seeing a pattern. was she convinced there was a killer in her own home? >> i think that she suspected it. she believed that there was an insurance policy on her. >> reporter: on her too. >> yeah. >> reporter: when you asked her to help you out, she said yes? >> she agreed. >> reporter: it was called operation abigail's, and it all went down at this local restaurant, known more for its

chicken wings than undercover stings. and "20/20" was taken right through it. so they walk in as a couple, and she's got the wire on where? >> underneath her clothing. >> reporter: and what does he think he's walking into? >> he thinks he's coming to talk to his wife about getting back together. >> reporter: about reconciliation? >> yes. >> reporter: but she has no plan to get back together? >> no. >> reporter: she's here for you? >> yes. >> reporter: cindy sat down with her husband, that wiretap hidden, with one intention, to catch karl karlsen on tape confessing to levi's murder, a confession she had told investigators he'd already made to her once before. >> reporter: so as they're sitting there at that table, how many other undercover investigators are here in the restaurant? >> a total of four. >> reporter: and this is what they got. >> i mean, you're sorry about it, right? >> every minute of every day. >> okay. karl, i -- i asked you if you pushed the truck, and you said yes. >> i didn't push the truck, i said. i said i had nothing to do, but

i said i took advantage of the situation once it happened. and that is exactly what i said to you. >> karl, you told me that you didn't set it up that way, but when you were in there, you saw the opportunity. >> no, after it had happened. then i panicked and saw the opportunity to where, like what you wrote, that's exactly what i said. >> one of the most significant remarks was that he took advantage of the opportunity. >> reporter: opportunity, a very strange word for a father to use about a son's death. >> i would find it very unusual that a parent would refer to the death of their child as an opportunity. >> reporter: a week later, karl karlsen agrees to meet his wife again. but cindy and that team of investigators have other plans. >> i'm all set. okay. >> reporter: so he thinks he's coming to meet her again? >> yes. >> reporter: but you're waiting for him this time. >> yes. >> reporter: and you haul him in for questioning. >> yes. >> reporter: how many hours? >> about nine and a half. >> reporter: when we come back, nine and a half hours, three different stories about his son

and that pickup truck. which one will you believe? >> you're that close, man. you're close. >> reporter: "20/20" inside the interrogation room. it is the first time anyone hears karl karlsen on the death of his son. not sure, but it what looks awesome. ♪ we heat the room to 110 degrees. huh? she's fine. on your right! what did you get? no clue, but it's jacked with protein. wow in a world filled with fads, it's nice to get back to basics. seriously dude? meat, cheese and nuts? seriously. new p3 portable protein pack from oscar mayer with 13g of serious protein. it's p3, it's oscar mayer.

new dream wonder foundation from maybelline new york. our unique micro-concealing formula is 12x thinner yet covers perfectly. it's flawless that's 100% traceless. new dream wonder. ♪ maybe it's maybelline new dream wonder. ♪ ♪ ♪ (announcer) tidy cats lightweight. with a clumping litter this light and just as strong at neutralizing odor, you'll want to say... (woman) hey! toss me that litter! (announcer) tidy cats lightweight. all the strength, half the weight. ♪ ooooohh!!! ♪ what it is, what you want? yeah. ♪ live your life right ♪ make the beat the bump ♪ the undeniable!

♪ come into the party in a b-boy stance ♪ i rock on the mic ♪ and make the world wanna dance ♪ fly like a dove ♪ that come from up above ♪ i'm rocking on the mic ♪ and you can call me mos love ♪ ooooohh!!! ♪ yeah yeah. yeah yeah. ♪ to make dinner more delicious. with eleven plump tomatoes in every jar, our sauce is richer, thicker and more delectable than ever. and bursting with so much taste, it brings families together. ragu. make dinner taste better. season mattress spectacularhe up to 60% off plus 10% off get an extra 5% or up to 60 months special financing and free delivery start your mattress search at sears where members get more. [ female announcer ] the magic begins when jif fresh roasts peanuts to make peanut butter so deliciously creamy. it can even bring a kid out of her shell.

that's why choosy moms choose jif. so i'm going pro. [ male announcer ] new crest tartar protection rinse. the only rinse that helps prevent tartar build-up and cavities. a little swishing. less scraping. yes! [ male announcer ] new crest pro-health tartar protection rinse. it helps you escape the scrape.

we return to "i know what you did." here's david muir. >> reporter: almost four years to the day after levi karlsen was crushed to death under a pickup truck, that insurance policy taken out just 17 days before, his father, the executor, karl karlsen now sitting inside this interrogation room across from investigators. >> what killed him? >> the truck. >> how did the truck kill him? >> it landed on him. and i had nothing to do with the truck landing on him. nothing. absolutely nothing. >> reporter: you haul him in and you begin asking questions. how many different stories did he have? >> three. >> reporter: version one, karlsen says he and his wife come home from a funeral and a dinner afterward to find levi

dead under the truck. but soon, version two, he was now saying that he and his wife were preparing to leave for at funeral when he discovered his son in the garage, pinned under the truck. >> the truck had already been fallen over. and i found him dead. and -- >> so this was around noon, you found, around noon or just before noon, you found him? you went out there, and the truck was rolled over on him? >> yeah. and i [ bleep ] panicked. i don't know. i don't know. >> so you, you panicked in what regard? >> just, i left him. >> now, you, you saw, did you run over and call medical help, call 911? did you get help? >> no, i didn't do anything. i, i [ bleep ] froze. >> now, was there a phone in the garage or a cell phone? >> no, no, no. >> or did you run back to the house and call 911? >> no. i, i went to the funeral. >> reporter: so he saw his son trapped and dead under the truck and still left for the funeral? >> yes. >> reporter: he says that father didn't return until four hours later. during the interrogation, karlsen asks repeatedly for his pain medication, medication he

says might have altered his behavior the day levi died. >> like i say whether it's partially to do with the medicine, i don't know. i, no, i don't play that card or whatever. >> reporter: and then several hours into the interrogation, karl karlsen appears to be on the verge of yet a third version of his story. >> i could never hurt him. i couldn't. >> you're that close, man. you're close. come on. let it out. let it out. let it out. i'll walk with you. man, i'll walk with you. was it just a split-second thing? >> i couldn't hurt him. it was an accident. i opened the truck door. >> okay. >> and when i did, it [ bleep ] with the wire. >> basically, how it's happened, we've gone from he was dead when you walked in there to now it fell when you opened the door. >> i know. >> so take the final step. >> there is no more.

i stepped in the truck and the [ bleep ] thing fell. and i was just [ bleep ] scared [ bleep ]. >> reporter: his son trapped by the truck and yet they still leave the house? >> yes. >> reporter: i mean, does that make any sense? >> no. i can't imagine walking away and leaving your child dying on the floor. >> reporter: they were going to a funeral. >> yes. >> reporter: and yet many would argue he had just created one right here in his own garage. >> it's fair to say that. >> reporter: but karl karlsen continued to insist he's innocent, opening up to the syracuse "post-standard" about his son from inside the county jail. >> well, levi, i mean, when he was younger, we had problems with him. school was hard for him. losing his first mother was really traumatic, would be for anybody. >> reporter: he talks about levi as a young father, that he took his son back in after levi's divorce.

>> my wife and i took him back in. and he, i decided to stick my neck out for him and told him what his responsibilities would be. he became responsible, he had manners, he grew up. and he realized that mom and dad weren't out to make his life miserable. he got life back into him. >> reporter: karlsen, now charged with murder in the second degree, entered the seneca county court house in december to enter his plea. and in a shocking moment of truth, he pleads guilty to killing his son levi. judge dennis bender sentencing karlsen to 15 years to life. levi's sister erin and her aunt colette say they're relieved but still hopeful investigators in california will charge karl karlsen in the death of his first wife too. >> i believe karl killed my sister. and he killed my nephew. and it's all linked to money.

>> reporter: and tonight, 23 years after that fire, a new investigation long after levi's death. the california d.a. has now announced they are charging karlsen with the murder of his first wife christine. >> and i wanna hear it from him. i wanna hear those words come out of his mouth. i want him to look me in my eye and tell me exactly what he did. and then i want him to go away for the rest of forever. >> when rereturn, he checked in, but never checked out. >> you open the door, and you see -- >> on the floor. >> was it a suicide? absolutely no one was in the room with him. >> i think i know how he died, and i think i know how we're going catch him.

♪ hanes. a perfect fit for every body. now in colorful new styles. ♪ you definitely should've tried applebee's new crosscut ribs by now. do you see these people resisting amazing sauces like sweet asian chile? no, you don't. and that's why they're happy. try new crosscut ribs. now all-you-can-eat for a limited time. only at applebee's. and come in late night for half-price apps. choose nexium twenty-foureople hour for frequent heartburn. i'd always wanted the protection of the purple pill®

now, i have it. get nexium level protection ™ and for a limited time save six dollars at nexium24hr.com big news! the hottest deal in wireless. whether you're a family of 2, 4, or 10, switch your whole family to sprint. you'll only pay $100 a month for unlimited talk and text and 20gb of high-speed data to share for only $100 a month for the whole account. that's double the high speed data of at&t, verizon and t-mobile. and to make it easier, we'll even buy out your whole family's contract. the sprint family share pack up to 10 lines for $100 a month simply put - it's the hottest deal in wireless. come in to a sprint store today.

(vo) ours is a world of the red-eyes. (daughter) i'm really tired. (vo) the transfers. well, that's kid number three. (vo) the co-pilots. all sitting... ...trusting... ...waiting...val. ...for a safe arrival. introducing the all-new subaru legacy.

designed to help the driver in you... ...care for the passenger in them. the subaru legacy. it's not just a sedan. it's a subaru. understandscount these days.aker count these days. that's why they have lots of ways for you to save. real big club card deals, the safeway app and gas rewards. time for a holiday get together. fresh sweet corn is 5 for just $1.00. grill up rancher's reserve ribeye steaks for only $7.99 a pound. and nabisco snack crackers are just $1.89. there's more savings to love... at safeway. ingredients for life.

we're going to turn next to another baffling mystery. he thought his crime would never catch up to him. what happens next is nearly impossible to believe. see if you can solve the case as fast as this private investigator, right in front of our "20/20" cameras. >> reporter: drive along interstate-10 long enough and eventually you'll run into beaumont, texas, home to big steer, big oil, and one big mystery. it happened here at the elegante hotel, not exactly the four seasons, although greg fleniken didn't mind it. he liked it here. but on september 15th, 2010, the oilman and devoted husband, seen here on hotel security footage, walked in and headed to his

room. hours later, he would check out in a body bag. >> he'll be missed and, by us that loved him. and such a good guy. >> reporter: when the sun rises that morning in texas, greg fleniken does not. detective scott apple is sent in. >> reporter: so you remember getting that call that thursday morning? >> yes, sir. and it just came in as a, a deceased person at one of our local hotels. >> reporter: with no clear signs of foul play, at first, the veteran detective thought this was going to be routine. you'd heard heavy smoker. >> mm-hmm. >> reporter: had been a drinker in the past. >> yes. >> reporter: a lot at stake. >> yes. >> reporter: so it wasn't. >> and never saw a doctor. >> reporter: so you thought this guy might have had a heart attack? >> that's what we had just figured it must be at the scene. >> reporter: detective apple heads to room 348. and inside that door, a 55-year-old man face down on the carpet. you open the door -- >> right. >> reporter: and you see -- >> greg fleniken on the floor. >> reporter: right there. >> yes, sir. >> reporter: in fact, there's nothing to suggest this is a crime scene at all. fleniken's cash is still in the room, candy and cigarettes on the bed, a soda on the table.

at first glance, it looks like this must have been death from natural causes. >> reporter: this room was his home away from home. >> right. >> reporter: greg fleniken had lived a good life. he had a great wife, success in the oil business, many friends and few, if any, enemies. >> he'd give you the, not only the shirt off his back but the shoes off his feet. >> reporter: friend miles martin met greg in the fourth grade in louisiana, and those boys from the bayou maintained a friendship ever since. >> i thought, well, those damn cigarettes. they finally, you know, they snuck up on him. >> reporter: inside room 348, detective apple says his initial investigation indicated that the victim had a regular, rather humdrum routine. fleniken, at home with his wife in louisiana on the weekends, but during the week, he would live out of a small suitcase here at the elegante doing pretty much the same thing every night. >> he'd set up, and that was his routine for the evenings. he had his phone to communicate with his wife or business. >> reporter: it seemed the travelling oilman had settled in for the evening. he just ordered "iron man 2" on

pay-per-view. >> he, he was a creature of habit, and that was his routine. >> reporter: but this cajun cowboy had taken his last ride to texas. all that was needed now was the medical examiner to list a cause of death. everyone thought the case would be closed. >> reporter: so his body is taken away to the medical examiner? >> right. and pending if he can just essentially confirm that it was a heart attack. >> reporter: dr. tommy brown, a fast-talking texan, was the medical examiner here. he was about to add a shocking twist to the case. brown would find that fleniken's body suffered severe internal damage, broken ribs, lacerations to the liver and scrotum, and a hole in his heart, all caused by blunt force trauma. but from what, and from whom? >> reporter: nothing had happened to him at work? nothing had fallen over on top of him in that room? >> there was no accident or anything happened to him on the way to the hotel, rather. >> reporter: no accident. in fact, the medical examiner was now ruling this death a homicide, convinced that someone

had killed him. >> reporter: did you ever think the ruling would be homicide? >> no. >> reporter: detective apple is a trained sniper, and he was now taking aim at multiple theories. >> could he have been seeing another woman or maybe there's a jealous husband? you know, but that's not greg. >> reporter: detective apple wants to know if anything odd happened at the elegante hotel that night. but aside from a circuit breaker needing repair in fleniken's room at 7:30 p.m., it was business as usual. apple questions the hotel guests in nearby rooms, but their answers offer little help. and who were they? >> they were some electricians out of wisconsin down here working at one of our refineries. >> reporter: that's electrician tim steinmetz and his colleague lance mueller entering the hotel with beer. they're later joined by fellow electrician trent pasano. you asked them had they heard anything that night? >> they said, "oh, we hardly ever saw him. we don't know." >> reporter: fleniken's cell phone records show nothing but a dutiful husband. >> it was pristine.

it was his business stuff, his stuff with his wife, family. that was it. >> reporter: the detective works tirelessly, but all he has is a dead guy, a bunch of dead ends, and as the days drag into weeks, a very angry widow. >> she would vent and yell at me. i can take that. i understand that. >> reporter: with the investigation seemingly losing steam in texas, a grieving and frustrated susie fleniken is desperate for answers. >> we need to know if anybody heard anything, saw anything, knows anything. >> things were basically stalled. and until she, you know, she took control over the situation at that point, and she hired her own investigator. >> reporter: and not just any investigator, but a former new york cop and federal agent now living in florida. his name is ken brennan, a man with a passion for crime solving, motorcycles, fine cigars and, yes, golf. >> reporter: so your phone rings. >> so my phone rings. >> reporter: do you remember where you were? >> yeah, i was on a golf course. hello?

>> reporter: and what does she say? >> that it's kind of getting to be a cold case going on the back burner. and she wanted to see if i could find out who killed her husband. the private eye is off to beaumont, texas, to get a better feel for the case. >> reporter: first thing you want to do is meet with the lead detective on the case. >> scott's one of those kind of guys. he's just a real cop's cop. and we hit it off really well the first night i met him. >> i'll start on the carpet. you can start in the back. >> reporter: this dynamic duo starting from scratch reviewing the case file, going through the hotel room like housekeeping, even taking a closer look at the victim. >> reporter: alcohol? >> no. >> reporter: drugs. >> no. >> reporter: pills? >> no. >> reporter: nothing. >> nothing. the only thing the guy did was smoke and eat candy bars. that was it. >> reporter: with more than $1,000 in cash still left in that hotel room, they rule out robbery. so instead, the investigators are now examining the security camera video, the broken circuit, some photographs. but none of them really feel like clues. there's simply no compelling theory, that is until

ken brennan has a classic a-ha moment and then shared it with his partner, that detective stumped. >> i said, "i think i know how this guy died." i said, "i think i know when it happened." i said, "i think i know who killed him, and i think i know how we're gonna catch him." >> reporter: the private eye convinced he's got it. have you figured it out yet? convinced he's got it. have you figured it out yet? when we come back. t new leggingp are at the top of our list... at kohl's labor day weekend sale. for junior's: find small prices on long leggings - $12.99 each and great brands and styles. levi's five eleven's for him $39.99 rock & republic for her. and can't miss savings for kids. pack in up to 50% off backpacks. and save big on shoes and boots for little feet. plus, everyone gets kohl's cash. thursday through saturday... at kohl's labor day weekend sale. find your yes. kohl's.

everybody's excited about the back at staples.avings from the customers, to the staples associates. with guaranteed low prices on comp books. you'll flip out! now go tell your friends. staples, make more happen for less.

"20/20" continues. once again, david muir, with "i know what you did." >> reporter: every hotel has its rules. but here at the elegante, they're actually written in stone. a "ten commandments" monument near the lobby reminds all, "thou shalt not kill." but somebody broke that rule, and greg fleniken paid the price. >> you know, there should be more people in this world like greg fleniken. >> reporter: unfortunately, he was stolen from his wife. >> yeah, exactly. >> reporter: by the time private investigator ken brennan rolls

into town, the body is cold and the leads are even colder. >> investigations are like a puzzle. a puzzle has many pieces. but each and every one of those pieces has to fit, and they have to fit perfectly. >> reporter: while the whodunit remains a mystery, the private investigator hones in on the when. >> this happened between 8:30 and 9:00 at night. he loved the room ice cold. his wife always said that, you know, he liked it like a meat locker. >> reporter: it was fleniken himself who, while watching "iron man 2" and making some popcorn in the microwave, tripped the circuit breaker. part of the hotel goes dark. >> so when they came in to reset the circuit breaker, i'm sure they shut everything down to reset the circuit breaker. so they shut off the air conditioning. >> reporter: it had to have happened in that window right after the maintenance guys left. >> he was killed before he realized that the room got warm. >> reporter: because he was so adamant about keeping the room freezing cold. >> ice cold, exactly. >> reporter: and when detectives discovered that body, the room was boiling. no one had turned that air conditioner back on.

brennan theorized that perhaps the hotel blackout could have led to an argument between fleniken and another guest who might have been ticked off. >> he must've had a confrontation. i said, "we're gonna find out that it was probably the two guys next door." >> reporter: dead men tell no tales, but brennan knows the living tell all sorts of stories. >> i know that if the guys next door had anything to do with this, they're not going to keep it to themselves. if they were involved at all, if they got in a confrontation, they're gonna tell their other coworkers. >> reporter: detective apple goes to find all of the coworkers of those three electricians staying next door to fleniken, tim steinmetz, lance mueller and trent pasano. no one knows anything, except for a supervisor who says he does recall hearing some story about a gun going off. the details don't seem to match the elegante killing, but brennan perks up. >> any time anybody tells a story, when somebody mentions something about a gun, that's the part they'll remember, the gun. >> reporter: more than eight

months into the case, it's the first time anyone has ever mentioned anything about a gun. >> detective apple thought that was just crazy. but ken brennan said, "no. we have to go check this out." >> reporter: they return to the scene of the crime, room 348. >> and they saw this indentation in the wall. >> reporter: in fact, maintenance records show that the wall in fleniken's room, room 348, had been repaired. but the indentation was noticeable, even in those crime scene photos. you notice some patching on the wall. >> yeah. so i said it's too big for a bullet hole, but let's see what it looks like on the other side. >> reporter: so now you're going into room 349? >> correct. >> reporter: and that's where the electricians were hanging out. >> let's go from the other side of the wall, put the dowel through the wall from where the bullet would've came from, put a laser on the end of that, and see what we have. >> reporter: i mean, you saw that laser -- >> right. >> reporter: go through the wall. >> right across top of the bed, right at the head of his pillow where he'd been laying. >> reporter: straight at the bed. >> straight at the bed. >> reporter: clear shot. >> clear shot. i said, "scott, this [ bleep ] was shot." at that point, we know exactly

what happened then. so i said, "we gotta get these guys." >> reporter: and you think someone must have fired a gun through that wall. >> somebody discharged a round through that wall. >> reporter: but has that private eye reached too far? remember, the autopsy never mentioned anything about a gunshot wound, the medical examiner listing the cause of death as blunt force trauma. the medical examiner, dr. brown? >> yes. he's been doing it a long time. he'd done some real good work. he's trusted. >> reporter: and what he says -- >> is gospel. >> reporter: respectfully, they now have to explain to the medical examiner they're rewriting his gospel. >> reporter: so you tell him your idea, and at first, he's not buying it? >> he's not buying it at all. and he says "hey," he says, "this guy was not shot. this guy was beaten to death." >> reporter: but brennan keeps sliding the proof toward the medical examiner, all of the photos, making this case that all of that internal damage, from the groin right up through the heart, was caused not by a kick from someone but from a bullet. >> i go, "doc, that's a bullet hole. come on." and he just looked, and he goes --

oh. >> reporter: his mind was changed. >> at least he was man enough that when we did show him physical evidence that was contrary to what he believed, that he was man enough to say, "okay, you're right." >> reporter: and while the cause of death has suddenly changed, will these men now change their stories? >> i don't know nothing, like i said. >> you don't think that we know the story, that we don't know what the hell went on here? of course, we know. what are you, a moron? >> reporter: a private eye preparing to jolt three electricians into telling the truth.

the nudes palette new from maybelline new york. our curated 12-shadow collection inspires infinite nude looks! from softly seductive. to deeply dramatic. get the look. new the nudes palette. ♪ maybe it's maybelline tlike chicken blanketed in golden breadcrumbs and wholesome sides with her signature touches. all topped with thick, homemade gravy. because dinner shouldn't take all day...

just taste like it did. marie callender's. it's time to savor new all-you-can-eat be the fcrosscut ribspplebee's and discover their tender bone-in flavor. just don't be the last to try them and their three irresistible sauces. i'm serious. do not be the last person. new crosscut ribs are now all-you-can-eat for a limited time. only at applebee's. and come in late night for half-price apps. season mattress spectacularhe up to 60% off plus 10% off get an extra 5% or up to 60 months special financing and free delivery start your mattress search at sears where members get more.

>> reporter: months go by, and those nomadic electricians in the room next door have long since departed texas. but now, convinced that greg fleniken was killed by a bullet fired from the neighboring hotel room where those electricians from wisconsin were staying, detective scott apple and private eye ken brennan travel there for a new round of interviews. they meet up at a local police department with electrician tim steinmetz, who once again appears courteous and curious. >> so what happened to this guy? did yoguys ever find out the whole point? >> reporter: time and time again, they ask him what he remembers. >> you didn't hear anything? you don't know anything that went on? absolutely no idea? >> no idea. >> reporter: steinmetz sticks to his original statement, that he, lance mueller, and trent pasano did nothing out of the ordinary that night. no mention of any gunshots. and steinmetz doesn't just tell that story, he swears to it in writing. >> i said, "let's get a notary as well and have it notarized so it looks even that much more official." >> do you swear everything this statement is the truth, the

whole truth, so help you god? >> yes. >> reporter: but just when he thought he was off the hook, investigators pull him back in. it was their plan all along. >> is that it? >> hang on a second. >> oh. >> it was until you signed that statement. now, you got a problem. >> okay. >> you don't think that we know the story, that we don't know what the hell went on here? of course, we know. what are you, a moron? >> you just made a -- false police report, that's why. you want to go to jail for that? >> tim, we know what happened. we know everything that happened down there. and i realize you're trying to be noble and protect a friend, but you're about to get your whole family in a bind, and it's not worth it. >> and after, the guy started thinking about that and he, and he says, "okay, i'll tell you the truth." >> no, i don't want to go to jail. >> well then, tell us what happened. >> reporter: steinmetz begins to reveal the pieces of the puzzle, explaining how the evening was fueled by alcohol, steinmetz and fellow electrician lance mueller entering the hotel with that beer. they're later joined by electrician trent pasano, and the heavy drinking begins next door in room 349.

>> it was an accident. it really was. >> reporter: it turns out mueller has a handgun in his truck and at some point, for some reason, steinmetz says the third electrician, trent pasano, goes to fetch it. >> we were in the room, and trent brought lance's freaking gun up there. and lance was [ bleep ] around with that gun. and he went and loaded it, pulled the freaking trigger, and the gun went off. >> reporter: later that day, they track down the third electrician, and trent pasano corroborates the story. listen as he explains how he nearly became the victim in this case, saying the bullet just missed him. >> and he goes, bam. and i went like this. son of a bitch. and i looked, and there was a hole, and it was smoking. >> reporter: it turns out that private eye was right, the bullet slicing through the wall in room 349 and heading directly

for fleniken, striking him in the groin area and shooting straight up to his heart, all while he was sitting there watching "iron man 2," all of that internal damage caused by a single shot from that 9-millimeter handgun. afterward, mueller quickly packing up the gun and returning it to his truck, exiting the hotel with a bag then returning moments later without it. and never telling anyone, those electricians try to cover both their tracks and that bullet hole. >> reporter: and what was it they put in there? >> toothpaste. >> reporter: they put toothpaste in the hole? >> mm-hmm. >> reporter: thinking no one would ever notice? >> exactly. >> reporter: no one went to check on greg. no one alerted the front desk. >> never bothered to knock, never bothered to put their ear to the door, heard any moaning or anything, nothing. >> reporter: the next day, even when they see a body carried out on a gurney from the room next door, they say nothing. >> this is not an accident, you know? this is a murder. >> he pulled that freaking trigger.

i sat right there and watched him do it. >> reporter: the only man missing at confession central was the shooter himself. watch as apple and brennan have steinmetz call the gunman. steinmetz urges mueller to turn himself in. >> i said they probably are going to come and get your ass. i don't, i don't know. but now that they know the truth and everything, you should probably try to make some kind of effort, you know? >> reporter: listen in as mueller realizes they figured it out. >> oh [ bleep ]. i mean, they're going to come and get me. >> reporter: he pleads no contest to a charge of manslaughter, a judge sentencing him to 10 years in prison. the others are not charged. >> i don't think he did the right thing. i don't think anybody did the right thing. >> reporter: inside that courthouse, susie fleniken watching on, saying it all could have been avoided had they simply checked on her husband that night. >> had he simply come forward, this would have been a completely different, quote, "accident." >> she was disgusted with their behavior.

she felt like they basically disregarded him as a human being. >> reporter: susie did not want to go on camera, trying to preserve that quiet life she and her husband once shared. but she did tell us of that private eye she hired, "i would trust him with my life." what did susie say to you?

with a new00 volkswagen turbo. reward card obsessed with turbo? because we like giving you power, but we also like giving you fuel efficiency. like the sporty jetta. and the turbocharged passat tdi® clean diesel. okay... and the iconic beetle... and the powerful tiguan... okay you can't forget the cc... guys, this is going to take a while. get a $1,000 reward card on new 2014 turbo models or lease a 2014 jetta se for $159 a month after a $1,000 bonus. ends soon!