got to make sure that you don't take any evidence for granted. up next, he made lots of money and liked to show it off. >> it wasn't a phase with him. that's how he lived. >> he was known to gamble, sometimes too much. >> he had had some gambling debts. he had some problems with the irs. >> when he ends up dead, his two ex-wives and a girlfriend are all suspects, but someone was sloppy. >> you can plan and plan and plan, but you'll never plan for everything. >> around 2002, the real estate market in the dallas/ft. worth area of texas was booming, and david nixon made a fortune. >> he had a very big personality.

he was always smiling. he was always happy. he liked nice things, nice clothes, nice cars, nice women. >> nixon primarily sold real estate in grapevine, texas, just outside dallas/ft. worth. >> it's a very vibrant city, very suburban. there is some money here, but the main focus is the lake. people want to live by it and have very nice homes around it. >> but david's idyllic life started to unravel one sunday night when his ex-wife walked into police headquarters to report him missing. she said he didn't show up for a dinner meeting with their 10-year-old son that evening, which was very unusual. she said he wasn't returning telephone calls either. >> david nixon was a great father who kept in contact with his son, even though he was divorced from his wife, and would constantly keep in contact with him. >> i can't really put my finger on anything.

i just have a gut feeling that there's something about this one that, you know, there's more to it than just the typical missing person. >> just a few hours later, a motorist ten miles away spotted a fire in the parking lot of an abandoned building. when he got closer, he was horrified to see what looked like a human body. >> the upper portion of the body was engulfed in flames. an accelerant was believed to have been used, like gasoline. >> the victim, wrapped in a blue tarp and a blanket, was clearly a large, white male with brown hair. dental records confirmed it was david nixon. >> looked like at some point, someone may have tried to stuff the body down the drainage ditch. the body wouldn't fit. >> if david's body had actually

gone all the way down into that 8-foot drain pipe, he might have never been found. >> friends and family were shocked by his murder. >> it's such a cruel way to die. to light someone on fire? >> there was no blood or any sign of a struggle, which meant david had likely been killed elsewhere. >> but it was clear that where the body was found was not the primary scene, that this was a dumping site and that the body had been set on fire to destroy potential evidence. >> and david's body had been wrapped in a blanket, a possible clue to the murder site. >> there was a group of filamentous wires, meaning very fine wires, from the charred remnants of the blanket. your typical blanket does not include metal fibers, unless it's a heat-generating blanket,

such as an electric blanket. >> a fractured rib alerted the medical examiner to a bullet pathway that led from david's left side through his heart. cause of death was a single gunshot. >> it was a small-caliber handgun. they couldn't determine, you know, what caliber, because we never found the bullet. >> to investigators, it seemed strange that david's ex-wife reported him missing just three hours before his body was found. and police soon learned she had a possible motive, a $500,000 motive. the future of kids? like a stock. not the kind of stock that's about making money. but a stock for social change. a whole new kind of investment called better futures. when you invest, it helps kids go to college.

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at david nixon's autopsy, the medical examiner discovered that david had been shot with a small-caliber bullet, and tests showed his body had been soaked with gasoline before the fire. despite the damage, the medical examiner was able to analyze undamaged tissue to estimate when david was shot. >> i was able to estimate that, at room temperature, the body was probably deceased for 36 to

48 hours prior to the body being discovered. >> since david's body was discovered sunday night past midnight, he was probably killed either late thursday night or early friday morning. david's murder bore striking similarities to another unsolved murder that occurred just four months earlier. >> it literally happened across the street. >> the victim, a 22-year-old prostitute named janet dolan, was killed with a single gunshot before her body was transported, doused with gasoline and set on fire. >> it would appear to be more like an execution or message-style murder when you have somebody shot and wrapped up and burned. >> but while the similarities between the cases were striking,

so were the differences. >> first of all, we had a female versus a male victim. >> david nixon was wealthy, had no criminal history and was not the type to put himself in harm's way. janet dolan was just the opposite. >> she probably put herself in some very strange situations with people she did not know. >> and janet's murder seemed to be a crime of opportunity, not something that had been planned. police concluded it was possible but highly unlikely the cases were connected. but investigators got a break when they discovered forensic evidence at david nixon's crime scene. there were tire impressions found within ten feet of david's body. >> it obviously, we believed, was the vehicle that transported him there. >> the tracks were from a

dual-axle vehicle, meaning it was a truck with two sets of tires on the back and one set on the front. >> there's two sets of tires, two sets of different tires, the front and rear. those had dramatically different tire tread impressions. >> but who wanted david nixon dead? >> the thing that i've seen when you're dealing with murder cases is there's generally two reasons people kill -- love and money. >> david's ex-wife, donna, had both of these motives. >> there were problems in david and donna's relationship. obviously, he left her for a young flight attendant, which of course, hurt her deeply. >> donna would also benefit from david's $500,000 insurance policy until their young son came of age. >> in crime investigating, one of the cardinal rules is follow the money. and of course, the ex-wife had just been named a beneficiary of an insurance policy, and the first thing police were going to do, under those circumstances,

was take a long, hard look at her. >> but donna was cooperating fully with the investigation and was an unlikely killer. she also had an alibi for thursday night and friday morning, the estimated time of death. >> as the investigation went along, it was clear that the evidence did not point in the direction of donna. >> david's second ex-wife also had an alibi for the time of david's murder, an alibi confirmed by numerous witnesses. next, investigators questioned david's current girlfriend, 32-year-old tracey frame. tracey said she last saw david on thursday, and she assumed he was headed to las vegas where he liked to gamble. >> you didn't hear from him any thursday night? >> no, sir. >> did you talk to him friday? >> no. >> nothing saturday? >> no. >> have not talked to him since? >> have not talked to him since then.

>> it was discovered that he had some gambling debts and he had some troubles with the irs. >> tracey consented to a search of the house she shared with david. >> we searched the home with luminol. we did a search with cadaver dogs. >> they found no evidence of blood, and the cadaver dogs didn't find anything either. but investigators did find one possible clue. >> as they searched the house, they found electric blanket controls, but they didn't find an electric blanket, which was kind of odd, because they found david wrapped in an electric blanket. >> a day later, police found david's white lexus abandoned in a supermarket parking lot within walking distance of their house. there was no blood or sign of violence in the car, but something immediately caught investigators' attention.

>> one of the first things investigators notice is that the seat is pushed up toward the steering wheel, which would indicate that a much smaller person had been in it last and not a big man like david nixon. >> investigators hope the store's security cameras might shed some light on who left david's car in the lot. q. bulldog: it's true! i am a bundle of talent!

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when police interviewed david nixon's live-in girlfriend, tracey frame, she claimed david was headed to las vegas on the night he disappeared. tracey also revealed she didn't have an alibi for the night david was murdered. she said she was at home alone. >> we, as a family, didn't really know much of anything. he didn't bring her up. i never spoke to her on the phone. she was a mystery to all of us really. >> a background check revealed the two had an interesting past. the couple met at a lake party shortly after david's second wife left him. tracey was a successful accountant with no children. shortly after they got together, david bought two matching cars, a black lexus for tracey, a white one for him. and because he owed back taxes

to the irs, david decided to place his house in tracey's name, a decision he came to regret. >> david wanted to regain control of the house, and tracey wanted to make sure that she kept the house in her name. >> but there was one seemingly insurmountable hurdle to her being a suspect. >> in looking at her, investigators had to decide how she could have moved the body. after all, although she was a trim and strong young woman, she was almost half the weight of david, and moving him would have been no easy task. >> then tracey's neighbors told police they saw a large rental truck parked at their house during the weekend david went missing. >> are you aware of a moving van be being at your house? >> i mean, he -- a moving van? >> like a u-haul, ryder? >> yeah. we were getting a truck to move

a -- some large stuff, the pool stuff, pool chairs that the dumpster wouldn't take. and they said that you'll have to move it. well, we don't have a vehicle, so david has done it a lot. >> next, police analyze the security video of the supermarket parking lot where they found david's car. at 1:47 p.m., just 37 minutes before david's burned body was found, a woman got out of david's white lexus, walked to a black lexus and drove away. >> you kind of look and go, you know, that looks like tracey, especially when she got in the black car. you're thinking, man. >> four hours earlier, the black lexus drove into the lot. the same woman got out, walked across the lot to a rental truck and drove away. tape showed that the previous afternoon, this same woman had parked the rental truck in the lot, then left on foot with a

large black dog. >> tracey had a large black dog. >> it does seem to be highly coincidental that the same person that you're looking at would also have a black lexus, a white lexus, access to a penske truck and to walk a dog similar to the one tracey frame had. >> because the camera was so far away, there was no way to positively identify the woman. if this was tracey frame, they'd need some way to prove it. >> what happened to david? >> what happened to him? i don't know. why are you asking me that? >> i'm asking you what happened to david. >> i don't know. >> what happened to david? >> i don't know. i don't know. >> tracey, we'll be honest with you. i think you do. in fact, there's a new victim of identity theft every...three...seconds.

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police had surveillance tape showing an unidentified woman parking two different cars in a shopping center parking lot next to a large rental truck. the two cars matched the make and model of those owned by david nixon and his girlfriend, tracey frame. police also had surveillance video of the same woman walking into the store on the night david's body was discovered.

>> wasn't able to really pick her up throughout the store, but could pick her up at the register again. >> the woman purchased garbage bags and two bottles of muriatic acid. >> although muriatic acid is sold in small amounts to private individuals, mostly it's used as a solvent or cleaner in heavy industry. >> that's when investigators noticed something important. in order to save 34 cents on her purchase, the woman used her discount card, and store records showed the name on the card was tracey frame. after the purchase, she drove away in the rental van. the rental agency told investigators they had rented that same truck to three other people in the days after tracey returned it. investigators found no blood or any trace of acid inside the truck, but the tire impressions

were potential evidence. >> my job was to see if there was any relation between the tires that were photographed of the moving vehicle and what was left at the scene. i was able to document that six different tires that had two different types of tire tread impressions, two different sets of class characteristics, were represented very neatly on the scene. >> this meant it was virtually certain tracey's moving van left these tire tracks. but one question remained. >> how does a woman tracey's size move a guy that large? >> the answer? a hand truck came with the moving vehicle. >> she merely has to place the hand truck on the bed beside him and roll him over on top of it and strap him to it.

then it's just a matter of pulling the hand truck around. >> investigators believe tracey knew david was planning to leave her, and she wanted to keep the house that was still in her name. late thursday night, as he slept, she shot him with an unregistered handgun friends said he kept in the house. she wrapped the body in blankets from the bed. the next day, friday, she drove david's car to the rental agency where she rented a moving van. she waited until nightfall and used a hand truck to get david's body into the van. then, she drove 14 miles to the isolated parking lot, where she tried to dispose of the body in a large drain, but it was too big. it wouldn't fit. she panicked and left, leaving

the tire impressions. worried that she'd have to explain why the moving van was parked at her house for an extended period, she parked it at the supermarket and walked home with her dog. on sunday night, she returned to the supermarket, bought trash bags and muriatic acid and identified herself by using her discount card to save 34 cents. that night, she cleaned the truck, doused david's body with gasoline, set it on fire, then exchanged vehicles again and returned home. once in custody, tracey was found to have linear bruises on her thighs at exactly the height the hand truck would have hit her body.

police also found evidence that tracey purchased a new mattress for her bedroom and had the old one removed. police believe that money was the motive. >> tracey was complaining about david one time to her friend carol. she said, well, why don't you just leave him? she said, well, without him, i'd be living in an apartment and driving a honda. >> in march of 2005, a jury took just four hours to convict tracey frame of first-degree murder. she was sentenced to 40 years in prison. she'll be eligible for parole after 20. >> police were looking at the totality of the coincidences. it was just too much for police not to determine that she was probably the one. >> the fact that, you know, she ran that card over and saved, i don't know, what was it, 34 cents, something like that? nice. >> science was this case, pure

and simple. i mean, there was -- there's really nothing else. that's what sealed it for her. >> you can plan and plan and plan, but you'll never plan for everything. up next, a young woman is missing and someone has stolen her identity. >> no one saw her leave, no one saw her arrive back at her apartment. >> but who wanted to harm her? >> she had received some harassing phone calls before her being reported missing. >> eventually the forensic evidence provided those answers. >> everybody an their brother were trying to make a deal with the devil. >> let he who has no sin cast the first stone, let me tell you i would have no problem casting all the stones. >> life was an adventure for 28-year-old denise o'neill. there was no trip she wouldn't take, virtually no activity she wouldn't try.