If any family typified the American dream it surely was the Ungers. Mark, 45, was a caring father and a successful mortgage broker. Florence, 43 combined being a wife and mother with a well-paid job as a retail buyer. Their two sons, Max, nine and six-year-old Tyler, were happy carefree youngsters good at sport and popular at school. The family home was an impressive split-level in an expensive suburb of Detroit.
There was enough money for frequent holidays and neighbours weren't surprised when in September 2003 at the start of the half-term holidays, the Ungers loaded up their estate-car for a four-hour drive to the holiday cottage they rented at Watervale on the shores of Lower Herring Lake, a beauty-spot in Michigan.
"Have a good trip," a neighbour called, as the smiling family drove away on what had all the ingredients of a dream holiday. Who could have guessed that within hours it would have turned into a deadly nightmare?
It was early evening when the family arrived at the lakeside cottage with its verandah deck and white-painted wooden walls. After dinner at one of their favourite restaurants — Watervale specialises in whitebait, salmon and trout from the lake — the family walked back to the cottage. According to Max and Tyler, their father told them to put on their pyjamas and watch a DVD before going to bed. "Your mum and I are going for a stroll by the lake," he told them. "We won't be long."
Mark later told police that after about 15 minutes darkness had fallen and Florence asked him to return to the cottage and make sure the boys were in bed. When he returned to the lakeside, she had disappeared.
"I thought she had gone to visit friends, Linn and Maggie Duncan, who had a cottage nearby, and I went back to the boys. I sat in a chair in the lounge and must have fallen asleep. When the boys woke me at 7.30 next morning, Florence had not come home.
"I was frantic with worry and phoned the Duncans but they hadn't seen her. They said they would come straight over and we would go look for Florence."
They didn't need to look far. As the Duncans walked over they saw Florence's body lying on the water's edge some distance from the Unger's cottage. They hurried to Mark and Linn told him "You're not going to like it. She's in the water."
Without waiting to hear any more, Mark Unger ran from the house to where his wife was floating in her dark tracksuit. He put his arms underneath her, but when unable to lift her weight, dropped her back into the water and stumbled ashore. Linn Duncan later told police: "How did he know where to find her? I never told him?" It was a question to which only Mark Unger would know the answer.
The first officer to arrive, Sheriff's deputy Troy Packard, noticed a pool of blood a short distance from the water's edge. If that was where she had been attacked, how had she ended up in the water?
During questioning, Unger was evasive. "I asked him to write a statement about what had happened and he kept answering: 'I don't know. I don't know', Deputy Packard said.
"He couldn't wait to leave. Even while Florence's body was still in the lake he had his bags packed in the car and ready to go. He never even asked what I thought had happened to her."
By nightfall, Mark Unger was the police's chief suspect and Florence's parents were given temporary custody of his sons. And when Unger was arrested on suspicion of murder, it gave police the chance to delve more deeply into the background of what appeared to be a happy and successful family. And what they found soon ripped away the flimsy facade that surrounded Mark and Florence's marriage.
Their lives had started to unravel in 1998 when Mark hurt his back and became addicted, first to painkillers, then to alcohol and gambling. He frittered away thousands of dollars at the roulette tables. Then at only 45 he decided to give up his well-paid job and stay at home. Florence was furious at having to become the breadwinner once more after enjoying her time as a stay-at-home mum. She now had to kick-start her career to pay the household bills and her husband's debts, and to pay him back started a low-key affair with one of his friends.
By now the marriage was in ruins but Mark still hoped that a quiet weekend in the cottage by the lake might just work a miracle. He told a close friend: "I thought that just maybe an idyllic weekend in the country might convince her we could try again. "If it didn't, we had divorce details to iron out and it was a good opportunity to try to do that amicably."
A neighbour also told police that before the trip to Watervale, she had found Florence crying in the garden. She said she was frightened of going because she feared something dreadful would happen. But she had decided to make the trip because her sons were looking forward to it. Police were convinced that during their late-evening walk Florence had refused to try to repair the marriage and had demanded a divorce. There had been a row which erupted in violence and Unger had killed his wife on the water's edge and then tried to stage it as a drowning accident.
But they had to prove it and Mark Unger had no intention of admitting anything. Only days after his wife's death he engaged a top defence lawyer, Bob Harrison, to put forward his claim that Florence had lost her balance and hit her head on a stone, causing fatal injuries. And when Unger eventually appeared in court Bob Harrison told the Michigan jury: "The police have no eye-witnesses, no fingerprints, no DNA, no murder weapon, no confession and no motive. It defies all reason that my client is even being charged."
Harrison, who had fought over 100 murder cases, was up against a formidable prosecution team headed by Donna Pendergast, who had won all but two of 93 murder cases and who claimed that the killing was premeditated. Pendergast told the court: "We say that Unger attacked his wife and left her unconscious while he tucked his sons up in bed. He then returned to drag Florence into the lake, where she drowned."
Slowly Donna Pendergast piled up a case against Mark Unger. Friends testified that Mark had told them the divorce would get ugly but he was determined to get the house and custody of the children. He also revealed that his wife's life was insured for $750,000...
But Bob Harrison, defending, painted a very different picture. He told the jury: "Mark loved Florence and had no reason to kill her. Her death was simply a tragic accident."
The defence claimed that after Mark had returned to the children, Florence had accidentally fallen from decking near the water's edge and in the darkness had mistakenly crawled into the lake and drowned. But the six-man-six-woman thought otherwise. They found Mark Unger guilty of first degree murder and he was gaoled for life without parole.
His mother, who had sold her house to pay for her only son's defence, sobbed in court while Florence's mother shouted: "Thank you, God!"
In a statement issued after the verdict, Mark Unger declared: "I would never hurt Florence. I want my boys to know that I would never harm their mother."
He is unlikely to be able to tell them this face-to-face. Florence's parents have adopted Max and Tyler on the stipulation that they never see their father again.