This story originally aired on Nov. 12, 2005.
Karen Tipton was in the prime of her life when she was brutally attacked and murdered in her home in Decatur, Ala., in 1999. Tipton's husband, a prominent doctor, was soon ruled out as a suspect, and the focus of the investigation shifted to a young man arrested several weeks after the crime.
Prosecutors viewed this as an open-and-shut case until the defense introduced issues related to alleged extra-marital affairs and use of pornography, and another theory on what may have led to Tipton's murder.
Correspondent Erin Moriarty reports.
David Tipton has tried hard to balance his day job as head psychiatrist at a mental hospital in Ahoskie, N.C., with his role as a single dad to 14-year-old Caroline and 10-year-old Catherine.
The girls say they are close to their dad, who has been raising his two daughters alone since his wife and their mother died in 1999.
Caroline says she misses her mom. "I do. What little I got to know her. I do miss her a lot." Caroline was 7 years old when her mother died; her sister Catherine was only 3.
And Caroline tells Catherine about their mother. "Yeah, every now and then it will be something like, 'OK, this is what she would have done. This is how she would have laughed and smiled.' Because that is probably what I remember most is just her smile."
David was a medical student when he met Karen Croft, a technician, at an Alabama hospital in 1984.
Karen's brother Lance and sister Laurie say that, after five years of dating, Karen announced David was the one.
"She said at one point, you know, 'He is just a great guy. He's going to make some person a great husband. It might as well be me,'" Laurie remembers.
They married on June 24, 1989, and soon moved to Decatur, Ala. Karen was looking forward to starting a family right away.
But almost 10 years later, on March 12, 1999, the family's life was shattered.
David Tipton says it was a perfectly normal day, and that they had made plans to see a show that night.
David says he came home from work earlier than usual. As he walked from the garage into the house, David says he noticed the deadbolt on the garage door was not locked. He thought it was a bit unusual but nothing "to go into a panic over."
Inside, David says he immediately spotted that the alarm panel had been removed and was lying on the kitchen counter.
"It was unusual, but it was not so weird. Given the fact that our alarm system was not working and we were expecting it to be fixed. But, yes, it was a little strange," David recalls, adding that the panel was on the wall when he left for work that morning.
As he went into the home's foyer to hang up his coat, David says he spotted a small drop of blood on a tile. "Then I look around, I'm going upstairs. I still think Karen's upstairs. It's a big house."
David says he called for his wife. He was also expecting his kids to be home at the time.
"The next thing I saw was more blood, in the foyer, toward the door, and it was smeared," remembers David. "I'm wondering if somebody has been hurt, come into the house, I'm wondering whether there really is nobody home because I'm calling up, not hearing anything."
"And I walked up the stairs and get to the top and find a dead body there that looked somewhat like Karen," says David.
Karen's nude body was at the top of stairs, viciously stabbed 28 times. Her killer had also cut her throat.
Daniel called 911 to report that his wife had been murdered, and he didn't know where his children were.