congratulations, guys. congratulations. reddish: thanks. now, this is actually the one business where you put up a little money and you hire somebody, you could replicate it. i could have. but what i like is they've got an existing book, and they're probably good foot soldiers. my man! whoo! whoo! [ both laugh ] rear naked choke on the counter. reddish: the definition of a good deal is when two people walk away a little unhappy. i think in this case mr. wonderful might have walked away a little too happy. but i guess only time will tell once we're on the cover forbes magazine.

to think that you can drop a 5,000 pound vehicle on your child and watch them die? >> tonight on 20/20, a series of bizarre and deadly freak accidents. >> 911. >> i need an ambulance. >> a beloved son crushed to death. >> the truck fell on my stepson. >> oh, my god! >> then what they uncovered from years earlier. what happened to the boy's mother? was it a family curse? or was there a cold blooded killer at the dinner table? >> a lot of people said when this guy needed money, a family member would die. tonight we're on the ground with investigators combing for clues. and a daring trap, when a new wife is terrified she could be next. the two of them are sitting at

this table. >> i asked you, if you pushed the truck. and you said yes. >> tonight, the 20/20 exclusive. >> you are that close, man. you're close. come on. let it out. >> the family member who now says i know what you did. >> here now, david muir. >> tonight, it's the explosive case about to go to trial, a son crushed under a 5,000 pound pickup truck, the dramatic call to 911, the parents and their cries for help. was the accident really a surprise to everyone? because when investigators start digging a shocking discovery. was there a deadly pattern to this family after all? tonight here the 20/20 exclusive, the daughter stepping forward to say, i know what you did. >> 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. so he was very mechanical.

>> reporter: and on one of those crisp fall days back in november 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 step-son. >> the truck fell on your step-son? >> 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 want to start cpr. do you know cpr? >> 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: and, at first it didn't appear to be anything out of the ordinary. >> no, it appeared to be an accident. >> reporter: a horrible accident. and 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. and long after 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." >> 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 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 told us the clues were immediate. red flag number one -- they discovered a brand new insurance policy for levi taken out 17 days before he died. >> well, that there's this large insurance policy that was collected on over $700,000 that was taken out only 17 days before his death. >> reporter: for the young man in the garage. 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: then, red flag number two. and who was the beneficiary? >> his father, mr. karlsen. >> 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: they soon began asking something else. just listen to red flag number three. you discovered a note written by levi? >> yes. >> reporter: that levi had left, saying what? >> that his father was going to be the sole executer of this estate and controlled, you know, basically dispersed the money to his kids, and that he did not want to be resuscitated. >> reporter: when was the letter notarized? >> the day of his death. >> reporter: the very same morning. and while investigators believe the evidence is damning, that karl karlsen planned his son's death, the whole town now trying to wrap their heads around this sinister plot. a plot levi's sister suspected from the very start. and tonight, for the first time, she's coming forward in a "20/20" exclusive. >> my father is a sociopath. the only one that matters to him is him. we were pawns in his game. >> reporter: her brother's death of cold blooded murder.

>> he had time to sit there and understand what was happening to him. >> reporter: and the killer she long suspected inside their own home, her father. she says they grew up in fear of their father and levi stayed in that town where they were raised, he had two young daughters, but 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 i don't know who they were, controlling everything. he wanted more than anything to just have a a close relationship with our father. he was really striving for that. >> reporter: she is convinced her father was crafting something else. the plan to kill his son. >> >> 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 scrap yard, where levi's pickup truck was taken to 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. 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. investigators do believe there was a railroad jack that day. unsure if there was anything else holding up that truck. what they do know is it came crashing down. you wouldn't stand a chance. >> you're gone. i mean, you're gone. >> reporter: when investigators begin asking how a father could do this, evidence of a pattern begins to mount. karl karl sen cashed in on insurance claims before. august 1986, a car fire, the

cause electrical, insurance payout $10,000. november 2002. a barn fire that killed three prized horses. cause, also electrical. 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 there on the 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. and tonight, only on "20/20," what his current wife feared next, and what she was willing to do to trap her husband. so you send her in through this parking lot, and she has a wire on where? >> underneath her clothing. >> reporter: what she got on tape when we come back.

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i know what you did continues. once again, david muir. >> reporter: when lieutenant john cleere re-opened 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 about to take all the way across the country, in a small mining town in the sierra foothills of california. and 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, died in a 1991 house fire. and who just happened to be the beneficiary of a $200,000 life insurance? her husband, karl. she'd been a vibrant, doting mother. you can see her holding one of

her three young children -- erin, levi and katie. >> we took walks. we went on picnics. we did crafts. you know, she taught me to cook, and was teaching me to sew. she literally did everything for me. she was just an amazing woman. >> reporter: but erin claims her mother was trapped in that marriage. >> my father had a very horrible temper, and it 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, you know, 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 years day 1991. the kids 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, you know, could feel the heat. i saw the flames, so 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 the 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. and when he left, christina's sister says he took with him any chance of a thorough investigation into her sister's death. >> we all raised our concerns, that we thought the fire looked very suspicious. the sheriff's department didn't want to waste their resources. they let this guy walk out of

the state of california and never went after him. >> reporter: that was 17 years ago. now two deaths, mother and son, each with a big payout for karl karlsen. was he a man cursed with a family tragedies? or 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 here. >> reporter: glenn coin, a reporter for the "syracuse post standard," has reported extensively on the case. >> 20 days before christina dies, karl takes out a $200,000 life insurance policy. 18-17 days before levi dies, karl takes out his $700,000 life insurance policy. according to the court records, he left both of them to die and walked away. >> reporter: tonight, authorities in california are now investigating too, after reopening the case of karl karlsen's first wife. and who was about to help investigate the take down? karl karlsen's second wife, cindy.

it would turn out his second and current wife, cindy, would play a critical role in the arrest of her own husband. >> reporter: you called his wife cindy. what did she say. >> thank god you called. >> reporter: she feared she could be next and moved out of their home she was afraid. >> yes. >> reporter: she was seeing a pattern. was she convinced there was a killer in her home? >> i think she suspected it. she could there was an insurance policy on her. >> reporter: on her, too. when you asked her to help her out. >> she agreed. >> reporter: it was called operation abigail and went down at this local restaurant known for more 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 plans to get back together?

>> no. >> reporter: she's here for you? >> yes. >> reporter: cindy sat down with her husband, that wire tap hidden, with one intention. to catch karl karlsen on tape confessing to levi's murder. a confession, she had told investigators, he had already made to her once before. they're sitting at a table, just the two of them. >> yes. >> reporter: and she's got a wire on the whole time? >> yes. >> reporter: as the couple is sitting here at the table, how many undercover investigators are sitting here in the restaurant? >> four. and this is what they got. >> i mean you're sorry about it, right? >> every minute of every day. >> i asked you if you pushed the truck, and you said yes. >> i didn't push the truck, i said. no. 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.

>> 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. >> yeah, i don't think a normal person would think of a death of their son 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. 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 pick up truck. which one will you believe? >> you're that close. you're close. >> reporter: "20/20" inside the interrogation room. and tonight, for the first time on network television, karl karlson from behind bars on

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you're unhappy for any reason. haggle-free buying... worry-free ownership. let us show you what that means. we continue with i know what you did. once again, david muir.

>> reporter: almost four years to the day after levi karlsen was crushed to death under a truck, that insurance policy taken out just 17 days before, and his father, the executor -- karl karlsen now sitting inside this interrogation room. across from investigators. >> what killed him? >> the truck. >> how'd the truck kill him? >> it landed on him. and i had nothing to do with the truck landing on him. nothing. absolutely nothing. >> reporter: so you haul him in and 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 that 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.

>> 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? >> and i [ bleep ] panicked. i don't know. i don't know. >> so you panicked in what regard? >> just --i left him. >> now you saw him did you run over and call medical help, call 911, did you get help? >> no, i didn't do anything. i [ bleep ] froze. >> now was there a phone in the garage? or a cell phone or did you run back to the house and call 911? >> no,i went to the funeral. >> reporter: so he saw his son dead and trapped 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, karl karlsen asks repeatedly for his pain medication during the interview, medication he says might have altered his behavior the day levi died. >> like i say if it was due to medicine, i don't know, i won't play that card or whatever. 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. >> couldn't do it. >> i'll walk with you. was it just a split second thing? >> i couldn't hurt him. i opened the truck door. >> okay. >> and when i did it -- [ bleep ] truck. we've gone from he was dead when you walked in there, to 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 ], i don't know why. >> reporter: his son trapped by the truck and yet they still leave the house? >> yes. >> reporter: 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: karl karlsen continues to insist he's innocent, opening up to the "syracuse post standard" about his son from inside the county jail where that father is sitting tonight. >> well, levi, i mean when he was younger, we had problems with him, um, um, school was hard for him. um, 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: as that father now awaits trial in the coming days -- his daughter, levi's sister erin and her aunt, collette say they're relieved their long-held suspicions will now play out in court. they're hopeful investigators in california will charge karl karlsen in the death of his first wife, too. >> i believe karl killed my sister. and because calaveras county didn't do their job, they enabled him to kill again. and he killed my nephew. and it's all linked to money. >> reporter: jurors will not hear about the death of his first wife. the judge ruling it's off limits. prosecutors must stick to what happened to levi. his sister erin wants answers for both loved ones. >> i want to hear it from him. i want to hear those words come out of his mouth. i want him to look in my eye and tell me exactly what he did.

and then i want him to go away for the rest of forever. >> reporter: so what do you make of the case, father accused of murdering his son for the insurance money. let us know on twitter use the #abc 2020. ever watch a movie in a hotel room, one man did and ended up dead. the mystery about to be solved in front of your eyes tonight. can you solve it before the private eye does. we didn't see this one coming. >> when we return, he checked in. but he never checked out. except in a body bag. >> you open the door and you see -- >> greg fleniken on the floor. >> how did he die, if it wasn't natural? was it a suicide? nobody had been in the room with him. >> i know how this guy died. i think i know when it happened. i think i know how we'll catch him. >> can you solve it? i know what you did next. well i trained em

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>> reporter: another baffling mystery tonight. a man sitting in a prison cell, he thought his crime would never catch up with him. this will make you think about the last time you were in a hotel room watching a movie.

because what happens next is nearly impossible to believe. tonight, see if you can solve the case as fast as one private eye is about to, cracking it wide open right in front of us. >> 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 season's, although greg fleniken didn't mind it. he liked it here. but on september 15th 2010, the oilman and devoted 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, but greg fleniken does not, detective scott apple is sent in. so you remember getting that call that thursday morning? >> yes, sir. and it just came in as 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: lot of steak. so it wasn't -- >> and never saw a doctor. >> reporter: so you thought this guy might have had a heart attack. >> and that's what we had just figured it must be at the scene. >> reporter: detective apple heads to room 348, and inside that door the 55-year-old man face down on the carpet. you open the door, and what do 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 bars and a soda are on the bed. at first glance, it looks like this must have been death from natural causes. this room was his home away from home. 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 4th 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 the victim had a regular, rather humdrum routine. at home with his wife in louisiana on the weekends, but during the week he lived 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 for business. >> reporter: it seemed the travelling oil man had settled in for the evening with his snacks and smokes. and he'd just ordered "iron man 2" on pay per view. >> 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, and everyone thought this case would be closed. 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. and 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? 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 home, on the way to the hotel. >> reporter: no accident. in fact, the medical examiner was now ruling this death a homicide, convinced that someone had killed him. 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 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 at working one of our refineries. >> reporter: that's electrician tim steinmetz and his colleague lance mueller entering the hotel with beer. they are later joined by fellow electrician trent pasano. and you asked them had they heard anything that night? >> and they said, "oh, we hardly ever saw him. we don't know anything." >> 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 call. 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 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. so your phone rings. >> so my phone rings. >> reporter: do you remember where you were? >> yeah, i was on a golf course. >> reporter: and what does she say? >> ken 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 investigator. >> we hit it off the first night i met him. >> reporter: this dynamic duo starting from scratch revealing the case file going through the hotel room like housekeeping. taking a closer look at the victim. 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 left in cash still in the hotel room, they rule out robbery. so instead the investigators examine 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 aha 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."

the private eye, convinced he's got it. have you figured it out yet? when we come back. falling and so are prices! are doritos, only $2.48. soapy rollbacks for only 6 bucks. and $30 on this 55" vizio. drillin' down prices. on this toshiba c series touch screen, save $49 on rollback. fun rollbacks. and pretty rollbacks. get more for your money at the october savings event going on right now at your local walmart! ♪ ♪ ♪ ♪ [ male announcer ] elevate your style. introducing the all-new corolla.

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david muir continues with the mystery in room 348. >> reporter: every hotel has its rules, but here at the elegante they're actually written in stone. a 10 commandments monument near the lobby reminds all -- "thou shalt not kill." but somebody broke that rule. and greg fleniken paid the price. >> uh, you know, there should be more people in this world like, uh, greg fleniken. >> reporter: unfortunately, he was, 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. and, uh, a puzzle has many pieces. but every one, 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 where" and "the when." >> this happened between

8:30 and 9:00 o'clock 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 "ironman 2" and making some popcorn in the microwave -- tripped the circuit breaker. part of the hotel goes dark. >> i said, 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 broiling. 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: brennan knows the living tell all sorts of stories. >> i know if the guys next door had anything to do with this, they won't keep it to themselves. they will tell their other co-workers. >> reporter: he goes to find the co-workers of the men staying next door. no one knows anything. except 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, nobody remembers, but when somebody mentions something about a gun, that's the part they'll remember. the gun. they don't remember anything else, but they 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 the wall in 348 had been repaired, but the indentation was noticeable in those crime scene photos. you notice some patching on the wall. >> so, i said it's too big for a bullet hole, but let's see what it says on the other side. >> reporter: so now, you're going into room 349. >> correct. >> reporter: 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: well you saw that laser. >> right. >> reporter: go through the wall. >> right across the top of the bed, right at the head of his pillow where he had been laying. >> straight at the bed. >> reporter: clear shot. >> clear shot. i said, "scott, this [ bleep ] was shot." at that point, we know exactly what happened. >> reporter: you think somebody must have shot the gun through that wall. has that private eye reached too far. the autopsy never mentioned anything about a gunshot wound. the medical examiner listing

cause of deaths as blunt force trauma. >> the medical examiner has been doing it a long time, he's done good work, he's trusted. what he says is gospel. >> reporter: they have to explain to the medical examiner their rewriting his gospel. so you tell him your idea, and at first, he's not buying it. >> he's not buying it at all. and, you know, he picked up on it right away, and he says, "hey." he says, "this -- 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 his 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, >> 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 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 prepares to jolt three electricians into telling the truth. >> just tell us what happened.

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20/20 continues. once again, david muir. >> 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 three 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 you guys ever find out? >> 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 in 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. 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. 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 says, "okay, i'll tell you the truth." >> no, i don't want to go to jail. >> 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 are 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 fricking 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 [ bleep ]. and i looked 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 the nine millimeter hand gun. 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. 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. >> 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. if they heard any moanin' or anything, nothing. >> reporter: and the next day, even when they see the guest 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 frigging 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 him to turn himself in. >> i said they probably are going to come and get your [ bleep ]. 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 gonna 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 the 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. >> reporter: what did susie say to you? >> was determined there would be corners and no way out. a man suspected of pining

police down. >> and a