Watching home videos of his family brings an instant smile to Mark Unger's face.
"It was love at first sight with Flo," said Unger. "She was my other half."
"Flo" was Florence, Mark Unger's wife of 13 years. She was an amateur photographer, who loved taking pictures of their children, Tyler and Max.
The family lived in an upscale Detroit suburb, but one of their favorite escapes was a peaceful lakeside resort called Watervale. It was there that 37-year-old Flo Unger lost her life.
Her husband was the only suspect, and in May 2004 Mark Unger was arrested and pleaded not guilty to the murder of his wife.
When Glenn Stark -- one of Mark Unger's closest friends -- reluctantly came forward, he admitted to having a secret two-year affair with Florence. He said he had sex with her days before she died. According to prosecutors, that affair was a possible motive.
But the defense challenged the prosecution, saying police work was shoddy and evidence nil. The crux of their defense was computer animations that created dramatic visual evidence of how Florence Unger may have fallen instead of being pushed. But was it enough?
Trip to the Lake Turns Bad
On Oct. 24, 2003, the Unger family were making the familiar four-hour drive from their home to Watervale.
But this wasn't like other family trips -- the Ungers had hit a patch of rough times.
Mark had become an alcoholic and gambled away thousands of dollars at casinos. He'd spent five months in rehab and decided that instead of going back to his job as a mortgage broker, he'd stay home and take care of the kids.
Friends say Flo was fed up and resented that she had to get a job; they said she had even started divorce proceedings.
Friends also said that Mark wanted to stay together and had convinced Flo the weekend away would be good for the family.
The Ungers were staying at a cottage called the "Mary Ellen" -- just a few hundred yards from the lake with its boat deck. It was a favorite spot for guests of the resort to have a glass of wine and watch evening sunsets.
On that October evening, Mark and Flo were outside talking on the deck. Soon after, Mark says Flo asked him to check on the boys, and he left her outside, alone in the dark.
Mark says he put the boys to bed and when he came back out -- more than an hour later -- his wife wasn't there.
Thinking his wife had gone to visit friends at another cottage, Mark said that he went inside to watch a DVD and fell asleep. When he awoke at about 7:30 in the morning, Mark said he realized Flo had never come home.
Mark said he called the friends -- Linn Duncan and his wife, Maggie, who own the resort -- in a panic, telling them Flo was missing.
They spread out to search, and the Duncans were the first to spot Flo Unger, lying face down in the cold shallow water.
"I looked down there I could see her in the water," said Linn Duncan. "And, I just, after a minute or so I started to cry. … My first reaction was suicide."
Linn walked up the hill and broke the news with four simple, devastating words.
"I said, 'She's in the water.' And he ran right to it. Right to the spot," Linn said.
The Duncans called 911, and Deputy Sheriff Troy Packard was first on the scene.
"I noticed that the top railing was broken, fractured out," Packard said. "Next I noticed a rather large pool of blood."
The pool of blood was on the cement platform directly under the deck, but Packard said he noticed something strange. There was no blood between that stain and where her body lay in the water several feet away, which raised a question in Packard's mind.
"How did Florence get in the water if there was no trail of blood leading from the original pool?" he said.
Packard spent about four hours talking to Mark Unger, and says he was struck by what he calls odd behavior.
He said Unger was vague when asked to write a statement about what happened the night before. And Packer said Unger wanted to leave the resort, even packing up the car while his wife's body was still in the lake.
Unger said he was shell-shocked and couldn't believe what was happening. "The whole thing has been a nightmare from the moment I saw her," he said.
Police had one theory and just one suspect in Flo's death. They suspect she was pushed off the deck on to the cement below, then dragged unconscious into the water where she drowned.
"By the end of that day, the time that I had spent with Mark Unger I was pretty much convinced in my mind that he was our suspect," Packard said.
Arrested, Defending Himself
From day one, Claire Stern suspected her son-in-law Mark Unger -- a former mortgage broker, a man with no criminal record or history of violence.
But in April 2004, six months after Flo Unger's death, there were still no charges filed. Mark said there was no evidence, because he was innocent.
"You couldn't write down ahead of time this scenario would take place. It would be too unreal. It's been a nightmare," he said.
Unger was locked in a custody battle over his sons with Flo's parents, who had succeeded in limiting is visitation to only a few hours a week.
"I try to leave a card every day for the kids and just let them know even though they don't see me I am right here," he said.
As the case exploded in the local headlines, Mark Unger spent his days defending himself even to people he thought were his friends. In the meantime, he was fighting to get his kids back; in family court, the Sterns' attorneys all but called him a murderer.
Bob Harrison, one of Detroit's most high-profile, high-priced defense attorneys, signed on to represent Unger.
Harrison said there was a very simple answer to what happened to Flo Unger that night -- she accidentally fell from the deck, whose railings were too low, rotting and unsafe.
Harrison even released a police report that concluded Flo Unger probably "lost her balance" and fell from the deck.
Unger seemed confident that he wouldn't be charged, but he was wrong.
On May 20, 2004, seven months after his wife's death, Mark Unger was arrested in front of his house while on his way to a baseball game.
"I was just shocked I mean totally shocked. I'm on the way to the ball field to set up hot dogs," he said.
At the arraignment, Unger looked stunned. His lawyer was late, and in a bizarre moment, he tried to represent himself at the bail hearing. He asked the judge to consider granting bail.
The judge warned Unger not to speak without counsel, then went on to deny him bond.
"That was about as low as I had been this whole time," Unger said. "I was just devastated, you know, I thought, 'Oh my God, I'm not gonna get out of jail.'"
But help wasn't far behind. A few minutes later, Unger was back in court with his defense attorney, Bob Harrison. Unger pleaded not guilty.
"We have no eyewitnesses no fingerprints, no confessions -- we have at most weak circumstantial evidence," Harrison told the judge.
After hearing from Harrison, the judge set bail at $100,000.
Unger was elated -- to him it was proof even the judge recognized the case against him was weak.
Circumstantial Evidence and an Unhappy Marriage
On the first day of his trial for murder, Unger was back at the Watervale resort. But he wasn't alone -- prosecutors, a judge and jury were there touring the scene as well.
Charged with the first-degree premeditated murder of his wife, Unger's bond had been revoked and he was back in jail. He had no contact with his children, and if convicted, faced life in prison.
Mark's mother, Bette Rosenthal, and Flo's mother, Claire Stern, sat on opposite sides of the courtroom.
It looked like a tough case for prosecutors Donna Pendergast and Mark Bilkovic. The evidence was entirely circumstantial, but they were confident they could prove it was murder.
The prosecution's theory was that on the night of Oct. 24, 2003, Mark and Flo Unger were on the deck at the Watervale resort, and during an argument, Mark pushed her.
They say Flo fell more than 12 feet onto the cement below and suffered critical head injuries. The prosecutors said that as she lay there unconscious -- but not dead -- Unger went back into the cottage and put their children to bed.
And here's where the premeditation part comes in -- they said Mark came back out and placed his wife face first in the water, where she drowned.
The trial began with friends and family describing the Unger's tense and unhappy marriage.
Kate Ostrove, one of Flo's best friends, told the jury that Mark and his wife had not shared a bedroom for about 2½ years.
Joan Frank, another friend, said Mark had recently completed five months in rehab for gambling and alcohol addiction but didn't want to go back to work -- so Flo had to.
"Flo has said to me that she was repulsed by Mark," Frank said. "I think she found the financial situation difficult. I think she found Mark was lazy and that was very hard for her."
In fact, Flo had filed for divorce that summer, and Mark had made it clear he would fight the divorce tooth and nail.
"Mark would say, 'I'm gonna take the kids and the house and give you like a thousand dollars to live on,'" Ostrove said.
Friends said Flo felt trapped, but agreed to go away that weekend for their children's sake.
Afraid of the Dark
Dori Turner, who co-owns the Watervale resort, said it was pitch black the night the Ungers arrived.
According to Mark Unger, he and his wife were out casually talking on the deck at about 9 p.m., when he left Flo alone to put the kids to bed in the cottage nearby. But Harold Stern, Flo's father, says she was always petrified of the dark.
The Ungers' neighbor, Kathy Stark, said Flo's fear was extreme.
"She would say, 'I left something in my car, I don't want to go out and get it,'" Stark said. "She wouldn't go outside. She would want us to come. I went a couple of times."
Saying he left his wife alone in the dark was just the first of many things Mark Unger said and did that weekend that didn't add up, according to prosecutors.
Mark says after putting the kids to bed he fell asleep and didn't realize his wife was gone till 7:30 the next morning.
He called Linn and Maggie Duncan, co-owners of the resort, asking for help. The first place they looked was the boat deck, which they could see from their front porch.
Mark, meanwhile, was searching the opposite end of the resort. Linn Duncan walked over and broke the news.
"He went ballistic," Linn said. "He started running, and he got to a railing. He went and jumped right in next to her."
Duncan said he hadn't told Unger where the body was. Prosecutors said there was no way he could have run directly to the body unless he knew where it was already.
Prosecutors also said Mark Unger's grief over his wife's death was unconvincing.
State police investigator Fran D'Angela told jurors, "He got noticeably upset, sobbing very loudly, but I never noticed any tears."
Deputy Sheriff Troy Packard was with Unger as he phoned loved ones to tell them the terrible news about Flo.
"He would erupt in this emotion, he would start crying, and be like 'I don't know, I don't know,' and then he would get a call waiting and he would click over and then he would turn it off, and he would be like, 'Hello,'" Packard said.
Stranger still to Packard, within two hours of finding his wife's body, Unger was packed up and ready to leave the resort with his sons.
"All he was saying, he just wanted to leave, and here is Florence still lying in the water, he never asked what I thought may have happened to her," Packard said.
As for physical evidence that Unger did anything to harm his wife, there was a small paint smear on Unger's shoe, which Keith Lamont analyzed for the prosecution. He said that the paint was consistent with the white paint from the railing and the pillar.
Prosecutors say after Unger pushed his wife over the deck, he kicked the railing to make it look like Flo's fall was an accident, and that's how he got paint on his shoe.
But the critical question was how Flo Unger got in the water.
Dr. Stephen Cohle performed the autopsy and testified that based on the swelling in her brain and amount of blood on the cement platform, Flo Unger must have laid there up to an hour and a half -- bleeding, but still alive.
"Well, it seems to me if one lands basically from 12 feet above on to a flat concrete surface, I don't think that her momentum would carry her into the water," Cohle said. "Whether or not she fell accidentally -- I have a hard time understanding how she got into the water."
The prosecution says Mark Unger deliberately drowned his wife, and their theory was bolstered by the testimony of Dr. L.J. Dragovic, a leading forensic neuropathologist.
"If you're placed in shallow water, if you're unconscious, you inhale water directly, you don't hold your breath, you don't fight, you inhale water directly, and that water goes in, and within a minute you're out. You're dead," Dragovic told the court.
Two-Year Love Affair Revealed
But what was the motive?
In a stunning moment in court, a reluctant witness came forward -- Glenn Stark, one of Mark Unger's closest friends.
On the stand Stark admitted to having a secret two-year affair with Florence Unger. In fact, he says he had sex with her just days before she died.
Prosecutors said that Flo could have told Mark about her affair that fateful night, and in a rage, he pushed her over the edge of the deck.
Glenn Stark testified that his friend never could seem to accept the idea Flo might truly leave him, and related a time he tried to give Mark advice about the impending divorce.
"I told him he needed to find a way to envision his life without Florence as his wife," Stark said. "He said he couldn't do that. ... He told me he couldn't do that, he loved her too much."
In his opening argument, defense attorney Bob Harrison described Mark Unger as devoted to his wife. "He was totally in love with her, he wanted her in his life forever," Harrison told the jury.
Harrison said Mark was the victim of inexperienced investigators who botched the crime scene, and that the case against him was totally circumstantial.
"There were no fingerprints in this case. There are no confessions in this case. No eyewitnesses to Mrs. Unger's fall in this case," Harrison said.
He laid out what he said was to blame for Flo's death, and it was not Mark Unger. He said it was the railing of the deck she was standing on before she died.
"You will see that it is so rotten that it can be smashed apart with my thumb and forefinger," Harrison said. "This was the support and protection that Flo Unger fell to her death from."
From the start, the defense was on the offensive, challenging the prosecution's theories, beginning with Flo's fear of the dark.
Harrison also offered an explanation as to why Mark Unger seemed in so much of a hurry to pack his car after his wife's body was found -- Lyle Walberg, Mark's nephew, says he suggested it.
"I said to Mark, 'You got to get the boys and you got to come home,'" Walberg said on the stand.
And Walberg rejected the notion that somehow his uncle was manufacturing his emotions.
"I've never had a man in my adult life hug me or cry as much -- it must have been 10 minutes of him and I just holding and embracing and tears from both of us," he said.
Defense attorney Tom McGuire then attacked the police work as shoddy. McGuire suggested the paint chip found on Mark Unger's shoe could have come from anywhere.
He also challenged one of the prosecution's key witnesses, Dr. Dragovic, who had testified he thought Flo Unger had drowned.
Even the prosecution's other key scientific witness, Dr. Stephen Cohle, testified Flo died from head trauma -- not drowning.
But the crux of the defense case involved the deck itself.
Even the cottage's owner Linn Duncan was forced to admit under cross-examination parts of it appeared in bad shape.
Wood expert John Zarzecki analyzed the deck. "The entire railing along that deck, lake side was completely rotted," he said. "It doesn't take any effort to break it apart into crumbs."
A structural engineer, David Ruby, said the railing was far lower than Michigan law requires. Ruby said the railing at the cottage measured 26 1/4 inches, while the minimum requirement under state law is 36 inches.
"When you lean against a rail 36 inches there's quite a bit of stability," Ruby testified. "When you lean against a rail 27 inches it's below your center of gravity, therefore, you have to create your balance, you have to create the stability. I'd say it was basically unsafe. "
To drive the point home, the defense unveiled one of its most important exhibits. Using a replica of the deck railing, retired MIT professor Igor Paul demonstrated for the jury how Flo Unger may have fallen accidentally.
Paul also showed the jury computer animations he created to explain how Flo may have fallen, left a blood stain on the cement and ended up rolling into the water.
The defense team felt they had provided compelling visual evidence casting doubt on the prosecution's claims.
Closing Arguments and a Verdict
After nearly two months of grim exhibits and emotional testimony, it was time for closing arguments.
Mark Unger was accused of first-degree murder, pushing his wife off a 12-foot deck then drowning her to make it look like an accident.
Defense attorney Bob Harrison reminded the jury that even the prosecution experts don't agree on the cause of death.
"They don't know how she went over. They don't know how she ended up in the water but they beg you to guess for them," he said. "
In their closing argument, prosecutors ridiculed the animation created by the retired MIT professor for the defense, which showed how Flo Unger could have fallen accidentally and rolled into the water.
They argued that the amount of brain swelling and the size of the blood stain showed that she lay on the cement platform for at least an hour, and that she was unconscious but alive before her husband put her face down in the cold shallow water.
With the case in the hands of the jury -- six men and six women -- Mark Unger waited alone in his jail cell to find out his fate.
Tuesday, June 20th 2006, the jury was still out on its third day of deliberations. Then, Wednesday afternoon, word came down that there was a verdict.
The anxiety in the courtroom was palpable, but Mark Unger seemed confident.
Then, when the verdict was read -- guilty of murder in the first degree -- Mark appeared stunned.
Flo's mother, who always believed her son-in-law was guilty, collapsed. Mark's mother, Bette, who sold her house in Florida to pay for his defense and has been at the trial every day, could only look on in disbelief as her son was led away in handcuffs.
Later, she said, "My son is innocent. He wouldn't hurt anyone. I think the world knows that…except for those people."
Mark's attorney, Bob Harrison, vowed to appeal. "This is not the end of this case for Mark Unger, we will appeal," he said.
The Ungers' sons, Max, now 13, and Tyler, now 10, are being raised by their grandmother Claire Stern.
"I want my daughter to rest in peace," Stern said. "When we went to her grave, and we did four times a week, we spoke to her, we said, 'Hang in there, darling, there will be justice.' And there was."
Mark Unger was sentenced to life in prison and is serving time in St. Louis Correctional Facility in Michigan. "Primetime" spoke to Mark Unger's attorney Bob Harrison this week, and he said that the appeal process is ongoing. A year after the trial, Unger's family remains angry over the sentencing, but hopeful of the appeal.
This report originally aired on June 22, 2006.