But over the years, two dramatically different versions have emerged of how Donnah Winger died -- and only one can be the truth.
There's the story told by her husband, Mark Winger. It's the account that police have, for the most part, accepted from the start -- that Winger killed an intruder who was attacking his wife.
And then there's the other version that seems much harder to believe -- that Winger had devised a complicated plot to murder his wife and frame another officer. Critical to this case is one police officer who had a hunch he couldn't let go.
Correspondent Richard Schlesinger updates this report that aired last summer.
Almost everyone who knew Mark and Donnah Winger thought they were perfect together.
"They were absolutely an adorable, model couple," says Sarah Jane Drescher, Donnah's mother.
Both were respected and successful members of their community. Mark was a nuclear engineer for the state of Illinois. Donnah was an operating room technician.
The Wingers wanted to start a family. But there was a problem. They learned Donnah could not bear children.
So when Donnah and Mark adopted a baby girl, Bailey, in June 1995, they were elated. "My heart was just pounding, I just couldn't believe it," says Winger.
But three months later, the good times ended abruptly. It all began when Donnah returned from a visit to her mother and stepfather in Florida.
Donnah and her baby arrived at the St. Louis airport and boarded an airport van for the 90-minute ride home to Springfield.
It was an unusual drive, with an unusual driver - a man named Roger Harrington, who had been working for the van company for six months.
Harrington was also speeding. "He was telling Donnah that sometimes when he drives, this God-like character would come to him and pull him out of his body and he would be flying above the trees," Winger remembers.
She and Bailey made it home, but Donnah was rattled. Mark Winger complained to Harrington's boss.
Less than a week later, Winger says, he was on his treadmill in the basement when he heard a thump. He says he went upstairs to investigate. Bailey, he says, was alone on his bed. And there were strange sounds coming from the dining room. "I just grabbed my gun and started going down the hall," says Winger.
When he came down the hallway, he said he saw his wife on the floor in the dining room. There was a stranger over her, bludgeoning her with a hammer. Winger shot the man in the head.
When police officers got there, they found two people bleeding on the floor. There was blood on the furniture, on the walls, even on the ceiling.
As paramedics went to work, Officer Dave Barringer took three quick pictures with his Polaroid camera. It was the last three pictures in his camera.
"I've been in crime scene work a long time and there's been very few that I've had that was as severe and bloody as this one was," says Det. Charlie Cox, who got right to work and questioned Winger in the bedroom.
Winger told the detectives the hammer was his, left out by Donnah as a reminder to hang a hat rack. He asked Cox a question: Who was the man he had shot? Cox told him it was Roger Harrington.
"He says, 'Oh my God, that's the guy that's been harassing my wife and me,'" recalls Cox.
"I think I fell over on my side and just cried," says Winger, believing that he would be taken in for killing another person.
But Winger couldn't have been more wrong. The police had all but cleared him. In fact, they didn't consider him a killer, they considered him a victim.
"I said, 'You've killed the person who was killing your wife,'" says Cox, who considered Winger a hero.
According to police reports, Winger said that Donnah was on her knees with Harrington leaning over her, attacking her with a hammer. Harrington looked up at him, and Winger shot him, because he was about to hit her again. He told police that at that point, Harrington fell off of Donnah and rolled back.
Cox's investigation of the crime scene backed up Winger's story. What's more, Harrington had been a psychiatric patient, with a history of delusions. Plus, Cox already knew him -- he once broke up a fight between Harrington and his wife.
Harrington died shortly after arriving at the hospital. Donnah died minutes later. She never regained consciousness.
Donnah's mother and stepfather, Sarah Jane and Ira Drescher, were inconsolable when they heard about the murder. They were shocked to hear that Donnah's ride from the airport had escalated into murder.
Donnah's family rushed to their son-in-law's side.
"We felt terrible for him. Look what he's lost. He's lost his wife also. And then he had to turn around and shoot a man," says Ira Drescher, Donnah's stepfather.
A day after the crime, the prosecutor announced that Mark had acted in self-defense, and that no charges would be filed against him.
The case was closed.
There was an outpouring of support for Mark in Springfield. Almost everyone believed he was a good family man whose life had been shattered by a madman.
But Roger Harrington's family wasn't buying the story. Harrington's sister, Barbara Howell, pleaded with Det. Cox to no avail. Harrington's mother, Helen, also felt the shame of a city that believed she had raised a psychotic killer.
The Harringtons grieved quietly, believing they were alone. But they didn't realize that Detective Doug Williamson was also not convinced of Harrington's guilt.
"Roger Harrington was allowed into the house. There was no forced entry. Somebody let him in," says Williamson. "Why would Donnah leave her baby alone on her bed and open the door to Harrington, a man she supposedly feared?"
Also, Harrington's car was parked right in front of the Winger home, with a piece of paper on the front seat: It had Mark Wingers name, his address and 4:30 p.m. written on it.
"[Mark] says he doesn't know Roger Harrington, has never met him, and does not indicate an appointment, when I have already seen the note which indicates an appointment," says Williamson.
Cox saw no reason to doubt Winger's story. But Williamson wanted to investigate further. His bosses turned him down.
The case stayed closed, until a shocking revelation years later.