their mother was appalling. and she did that. she's the one that did that. up next, a family vacation turns to a nightmare. >> that's when i see the body of a female lying face down in the water. >> and possible clues provide more questions than answers. >> either it was an accident, someone caused her death, or she killed herself. >> experts can't seem to agree on exactly what happened. >> there is not one single eyewitness to anything. there are no confessions. there are no fingerprints. >> until ground breaking science discovers the truth. >> method, opportunity, motive, and last person to see them alive. classic reasons for murder. >> every year the unger family spent their vacation on lake michigan in a place called watervale.

>> it's a sanctuary for them where they can go to forget about the rest of the world and reconnect with themselves and their families and the loved ones. >> florence worked as a bank loan officer. her husband mark, a mortgage broker, was also a well known radio personality. >> mark unger had a sports radio show and was somewhat of a celebrity in a circle of friends. >> their vacation in 2003 was like most others. the ungers had checked into their cabin, had dinner, and mark spent time with their two sons while florence was outside for fresh air. >> mark read a story with the boys, kissed them good night, came back out to the deck and florence was not on the deck. >> mark assumed florence went next door to the friends' cabin

since the lights were on. not wanting to leave the children alone, mark went to bed. when he awoke just after dawn, florence still wasn't there. >> he called the resort owners approximately 7:30 in the morning asking them if they had seen florence. they said they had not. >> the resort owners went looking for her and found florence's body in the lake and called 911. >> there was a death at watervale who is an acquaintance of ours and i believe it was a suicide or drowning. >> what was her name? >> florence unger. >> when police arrived, they noticed florence's body was in the lake next to a boat launch. 12 feet above was the deck outside the unger's cabin. >> when i looked up, there was a

deck railing from the boat house and i noticed the deck railing was broke and fractured out. >> it looked as if florence had been sitting on the railing and it gave way. investigators measured the height of the railing and discovered that it was ten inches below the state building code. >> you look at that and think if somebody had been sitting on it, they could lose their balance and fall over the edge. i know i personally didn't want to sit on it. >> the splintered railing led to suspicions it was structurally unsound. >> they referred to it as a death trap and it was an accident waiting to happen. >> a person could reasonably piece together someone fell through a railing, hit the ground, and ended up perhaps in the lake there. >> florence's body was transported to the medical examiner for an autopsy. the medical examiner found no drugs or alcohol in her system.

he did find evidence of severe head trauma. but the cause of death wasn't the head trauma. it was drowning. >> there was plenty of fluid and that was the result of her active inhalation of the water from the lake. because she was submerged. >> but what caused florence to fall to her death? was it suicide? an accident? or something more sinister? you'e expanded your business? after your company's gone public? and the capital's been invested? or when your company's bought another? is it over after you've given back? you never stop achieving. that's why, at barclays, our ambition is to always realize yours.

this is flo unger. she was a student from 1975 to 1978. >> the tragic death of florence unger, the mother of two young children, was a shock to coworkers, friends, and family. >> unless you'd lived through it, it's difficult to explain. you feel like your head's going to explode. it's total and complete devastation. there's nothing like it. it's unimaginable. >> police at the scene had to consider every possibility. >> do you have a suicide? do you have an accident? or do you have a homicide? >> florence's family ruled out suicide as a possibility. >> there's no way that she could have contemplated suicide for a

number of reasons. number one, she would have never left her children parentless. >> an accident seemed like a distinct possibility. the railing on the deck outside the ungers' cabin was freshly broken. it looked as if she were sitting or leaning on it and it gave way. causing her to fall to the boat launch below. but how did the body get into the water? mark unger hired a private independent forensic firm to find out why. they concluded that with florence falling 12 feet from the deck, the momentum of the fall carried her forward from the point of impact. >> they produced five different scenarios, computer animations that showed different ways that florence could have possibly ended up in the water. >> the forensic firm concluded that florence's death was an accident.

but the medical examiner completely disagreed. >> bodies do not bounce. that's number one. she would have been rendered unconscious upon contact. an unconscious individual cannot just walk into the water. >> and dr. dragovic noticed the blood stain on the boat launch was nearly a foot in diameter. >> for blood to go to that size to the diameter that we're talking on the cement platform, the body would have had to have been there for a period of time. >> to find out how long florence would have laid there bleeding, dr. dragovic examined slides of her brain tissue. he focused on the neurons. a cellar communication system that controls movement, memory, and emotion. he discovered proteins in her brain that were released after her head injury. this showed that florence's brain was struggling to survive long after she hit her head and

before she drowned. dr. dragovic estimated that florence was lying on the cement for at least 90 minutes, possibly for as long as two hours before she was in the water. and there was other conflicting evidence. the blood stain on the boat launch and the broken railing above did not line up. >> the trajectory of where she wound up on the deck was not in line with where the break in the railing occurred. >> to see whether the deck

railing was structurally unsound, analysts tested an unbroken section of the deck railing using what's called a load cell. >> the load cell is more or less a scale. it's a series of springs and sensors. and it measures compression and tension. >> florence weighed 110 pounds. to simulate her sitting on the railing, analysts attached a bicycle seat to one end of the load cell. to the other end, they attached a t-bar to which they applied 200 pounds of pressure. the railing didn't buckle or break. >> somebody from the lab made the comment, wow 200 pounds. we knew right then and there that any plan to paint the rail as rotting and dilapidated weren't going to work. >> it was beginning to look like the scene had been staged to look like an accident. it was a charge florence's husband mark adamantly denied. >> people that knew mark said mark was not a killer. mark would not do that. that he loved flo, that he loved

his family, that he would not do that. >> mark had no criminal history. and his children said they heard nothing suspicious on the night of the incident. no argument or fight between their mother and father. mark continued to maintain his wife's death was a tragic accident. but florence's family believed this was murder. and that mark was her killer. >> method, opportunity, motive, d buy them their own, let alone for under $300. but this asus with windows is lightweight and has everything they need -- not like chromebooks that can't install office or have to be connected to the internet to get much done. with this they can do homework, chat, play games -- on their own laptop, and their own time. so no more fighting...

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of the sochi olympics, now on your tv. the x1 entertainment operating system, only from xfinity. mark and florence unger appeared to have an ideal marriage. >> on the surface, they would appear to be the perfect couple living in an affluent community with two beautiful children, a beautiful house. but those who were in their inner circle, they knew that there were many, many problems. >> mark unger's issues with drugs and gambling had cost him his job. >> he was a pathological gambler. mark was an alcoholic. he was a drug addict. and this was affecting his personality. >> he spent as much as six months at a time in rehab. >> florence actually said at one

point it almost seemed like rehabilitation had become his job. >> police also learned that florence had filed for divorce two months before her death, and had moved on to another relationship. >> there was evidence of a relationship that flo had become involved in. and this individual was a close friend of mark's as well. so it was a -- a difficult circumstance at best. >> investigators discovered that florence had seen this man just a few days before her death, and that mark might have known about it. >> i believe on that deck, that it's a very real possibility that something about florence's relationship came out. >> and now yet another potential motive emerged. florence had two life insurance policies with a combined value of 3/4 of a million dollars. and mark was the sole beneficiary. >> there's no question that flo was worth more dead to mark than

she was alive. >> even stranger, just five days before his wife's death, mark had a run of bad luck at a local casino. >> we understand he lost about $7,000 shortly before the fateful trip. and i mean within days of that fateful trip. >> and friends told investigators florence didn't want to take the trip to the lake. in fact, she was afraid to go. >> flo's friends were all apprehensive. several of her friends asked why are you doing this? why are you going up there? >> she did not want to go. she was afraid to go. she admitted that to a neighbor. >> and if that weren't enough, the resort owner gave police more evidence. also circumstantial.

he said when he told mark he had found florence's body, mark didn't ask him where it was. >> he resort owner absolutely positively testified that he did not tell mark where flo was, florence was. >> but mark appeared to know exactly where to go. >> mark ran right to florence's body lying in the water without being told where she was at and without being able to observe her from his vantage point. >> to prove this, investigators placed a mannequin in the water exactly where florence's body was found. then an investigator with a

video camera stood at the exact spot where the resort owner told mark his wife was dead. in this videotape, it's clear the body can't be seen until the viewer is virtually on top of it. >> he knew exactly where the body was at. >> but none of this proved murder. in fact, investigators had no direct evidence linking mark to florence's death. that is, until they looked at mark unger's shoes and found a white smear. >> the state police crime lab found a white speck of what they believe was paint. >> investigators sent mark's shoe along with six different paint samples collected from the resort to forensic scientist keith lamont. >> i received several specimens from the resort area. >> he bombarded the sample with infrared light which shows the sample in ways that can then be measured. >> paints composition basically

consists of a solvent which is a liquid. a pigment which is color. and a binder. and the binder you can think of as glue. >> lamont found that the paint on mark unger's shoe was virtually identical to the paint on the railing. and the post holding the railing. >> the example from the shoe was consistent with the paint from the rail. >> to investigators, this pointed to only one logical conclusion. >> we believe mark kicked that railing. the paint on the shoes would suggest that. >> but was this enough to get a conviction?

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investigators knew two important details about the death of florence unger. first tests showed a 110 pound woman sitting or leaning against the deck railing could not have caused it to splinter. second, forensic tests identified repair proteins in florence's brain. scientific proof that she laid bleeding on the boat launch for about 90 minutes before the drowned in the lake. this made forensic history. it was the first time immunohisto chemistry was used in a case. seven months after florence's death, mark unger was charged

with first degree murder. >> there's no doubt he made a calculated decision to take another person's life. >> his lawyer said there was no case against him. >> there is not one single eyewitness to anything, there are no confessions, there are no fingerprints. >> prosecutors believe mark hoped to salvage their marriage, but they think florence said no. mark became violent and pushed her over the railing. she hit her head on the boat launch 12 feet below. the evidence indicates she lay there bleeding for at least 90 minutes. mark went back to their cabin and put the boys to bed. when he returned to the boat launch, he was probably surprised to learn that florence was still alive. so he pushed her into the lake where she drowned. but he didn't realize the size of the blood stain on the boat launch. and the repair neurons in

florence's brain. both told a story. in an attempt to make it look like an accident, mark kicked the railing with his right foot transferring paint to the tip of his shoe. and where he kicked the railing was inconsistent with the location of the body. >> he had every opportunity to call for help. he never did. he let her lay there. and after thinking about what to do for some time, he premeditated it. he went back and pushed her in the water to drown. >> three years after florence's death, mark unger was convicted to first degree murder and sentenced to life without parole. >> his head snapped back when

that verdict was read. he was shocked at the verdict. he anticipated going home that day. >> i was wrongfully convicted of this crime. i am innocent. >> florence's parents say her death should never have happened. >> while my daughter's death was a tragic and unnecessary event, i think there's a lesson to be learned from it. and that is that a woman who is going through a divorce should avoid contact with her estranged husband unless it's absolutely necessary. and then with witnesses present. and even though it might be contrary to the advice of her lawyer, and even if there is no history of mental or physical abuse. divorce is a very volatile situation. and it is better to ere on the side of caution.

because even casual contact could result in a dangerous or life threatening event. >> florence's parents are raising her children and keep a small garden in her memory. although the grief is permanent. >> i miss her every single minute of every single day. and i hope he thinks about what he's done for the rest of his miserable life. >> mark unger almost got away with murder. only scientific analysis of brain tissue and his shoes ensured he didn't. >> how he could think he was going to get away with it, i can't imagine. >> being able to establish that florence was alive for an extended period of time before she was placed in the water was crucial, very important.

>> it was a great reminder that things aren't always as what they seem. not always what people try to portray them to be. up next, it looked like a joyride, but was something much worse. >> she was going to jump out of the back of the truck while it was moving. >> we just thought it was a crazy drunk person, you know, just partying. >> the evidence suggests foul play. >> all we knew was that there