Michele Somers was a 20-year-old beauty queen when she met her future husband, Martin MacNeill, in 1977 in California. They had a whirlwind romance and eloped just months after they had met. <a href="http://abc.go.com/watch/2020/SH559026/VD55114572/2020-225-macneills-death-foul-playills-murder" target="external">CLICK HERE to watch the full story on on the latest episode of '20/20.' </a>

Michele and Martin MacNeill made a striking couple. But Michele's family was not impressed by Martin, said her sister Linda. "Right away I saw that he was arrogant…I felt like he was…deceitful, and there was something, just not right with him," she said.

Soon after Michele and Martin married, they started a family. Michele gave birth to four children in five years, raising them in Washington and Utah. Martin got his medical degree in osteopathy and the family lived a comfortable and apparently happy life.

After Michele and Martin's four biological children were grown, they adopted four young girls, three of them from Ukraine. Daughter Alexis remembers her childhood as a happy one. "I had a wonderful childhood. ..My mom was always there and just the best person," she said. Her relationship with her father was also loving and she looked up to him. "I always wanted to be a doctor just like him."

In 2006 and 2007, Martin MacNeill's behavior became "bizarre," according to daughters Alexis and Rachel. He began going to tanning salons and exercising a great deal. And then, seemingly out of the blue, his daughters say he suggested to his 50-year-old wife, Michele, that she get a facelift. After some convincing, she agreed to it.

On April 11, 2007, the seemingly perfect world in which the MacNeill family lived came crashing down. One week after Michele's facelift, she was found unconscious in her bathtub by six-year old Ada MacNeill, and then by Martin who administered CPR and called 911. The medical examiner ruled her death was natural, caused by hypertension and a heart infection. But her daughter, Alexis, suspected that her father had a hand in her mother's death.

Martin MacNeill was allegedly having an affair with a woman named Gypsy Willis during his marriage to Michele. Investigators say they met on the Internet. Just two weeks after Michele's death, Martin hired Gypsy as the "nanny" to take care of the younger MacNeill children. She moved into the family home.

After a legal battle with her father, Alexis gained custody of the three youngest sisters. During this time, sisters Alexis and Rachel, along with their aunt, Linda Cluff, say they pursued their suspicions about Martin -- pleading with officials to investigate him and the death of Michele MacNeill.

After a year and a half, Doug Witney, an investigator for the Utah County Attorney's office, took over the case and began to uncover some troubling details. Here, he speaks with 2020 anchor Elizabeth Vargas outside the MacNeill family home in Pleasant Grove, Utah.

Utah County investigator Doug Witney uncovered Dr. Martin MacNeill's secret and criminal past. Witney learned that MacNeill had used a fake transcript to get into medical school, and was even convicted of check fraud in 1977. "I believe that Martin MacNeill is a sociopath," said Witney. "I believe that he has very little conscience about things that he has done to other people."

While uncovering details of MacNeill's past, Utah County investigator Doug Witney discovered that MacNeill and his girlfriend, Gypsy Willis, together committed identity theft and fraud.

Martin MacNeill and Gypsy Willis were arrested in January 2009. They are serving time in separate federal prisons for charges of fraud and identity theft. Rachel MacNeill reflected on the father she believed she knew: "We basically found out that our entire lives had been based and surrounded on lies -- that everything about our experience with our father was a lie."

The investigation into Michele MacNeill's death continues. Martin MacNeill maintains that his wife collapsed while drawing a bath and no charges have been filed. On Jan. 15, 2011, Michele would have turned 54. Daughter Alexis says she believes that if her mother had known of her father's deception and infidelity, she would not have stayed with him. "If she would have known who my father was, she would have been gone in a minute. She would have wanted to protect her children and she would not have stayed if she would have known what was going on. " <a href="http://abc.go.com/watch/2020/SH559026/VD55114572/2020-225-macneills-death-foul-playills-murder" target="external">CLICK HERE to watch the full story on on the latest episode of '20/20.' </a>