On a July night, a group of friends at the University of Kentucky celebrated a 21st birthday party at an off-campus house.
At the center of that low-key gathering was Trent DiGiuro. A rising senior at the school that summer in 1994, DiGiuro was a lifelong football player who decided to try his luck as a walk-on for the Kentucky Wildcats. After years of hard work, he earned a starting position.
"Everyone called him a big teddy bear," childhood friend Peyton Turner recalled. "He was the great protector of all of our friends."
That night, as the birthday party wound down, DiGiuro and a few friends gathered on the front porch. Suddenly, a loud noise rang out.
Antonio O'Ferral, DiGiuro's roommate and the team's quarterback at the time, had just gone to bed when he heard it.
"You started to hear the chaos outside," he recalled later. "The screaming, the yelling, the crying."
DiGiuro was slumped over in his chair and bleeding. He had been shot, and was pronounced dead at 3 a.m.
Don Evans, a Lexington police detective, arrived at the scene around the same time. Since there was a party that night, he figured there must be people who saw something.
"But with each and every person that I talked to, they didn't see anything," said Evans, who has since retired from the department.
Left with more questions than answers — and few credible leads — the case went cold for years. For Evans, a rookie detective, it was intensely personal: It was his first-ever case.
"You're four years in, five years in, and really no closer to solving it than day one," Evans said. "It will make you doubt yourself."
Friends and family had begun to accept the hard truth that DiGiuro's killing would remain unsolved. Then, five years after his death, a local newspaper published an article about him in which his father made a plea for information to the public: "Somebody knows what happened."
And somebody did come forward: A young woman with an unbelievable story. About a year after DiGiuro was killed, she was at a local bar with her then-boyfriend. The conversation turned personal. What was the worst thing they had ever done?
"I killed Trent DiGiuro," the boyfriend said.
But the woman was in love, she said, and didn't want to think he was capable of something so awful. She put it out of her mind, and their relationship continued.
On the five-year anniversary of Trent’s death, the woman saw an article in a newspaper where Trent’s dad was quoted as saying “somebody knows what happened.” Now, years later, she felt compelled to share what she knew.
So she went to an old friend, an attorney in Lexington, for advice. She was vague at first, asking if she could she report a crime without revealing who she was. "She eventually came around to say it was a very high-profile murder," said Tom Bullock, her friend. "I knew which one it was."
But the woman was frightened to go public, fearing her ex-boyfriend would come after her.
Bullock went to Evans with information without revealing his source. He gave him the name of the alleged killer: Shane Ragland, who attended the University of Kentucky the same time as DiGiuro.
And he told him the alleged motive for the shooting. It was astounding — Ragland blamed DiGiuro for being blackballed from a fraternity.
Evans realized he might be on to something, and knew he had to meet this anonymous source to continue his investigation. The woman eventually agreed to cooperate with him. That involved taking part in a risky sting operation with the goal of getting Ragland to talk about killing DiGiuro — and to get it on tape.
So she resumed contact with Ragland, and he took the bait. After exchanging emails and talking on the phone, they arranged to meet at the Lexington airport, where she said she'd be passing through on business.
Nearly six years to the day after DiGiuro's death, the pair met and she wore a wire — and was surrounded by undercover cops and undercover FBI. They talked about old times for a while, and then she subtly brought up the terrible secret he had confessed to her.
"I regret it," Ragland said.
"You do, now?" she asked.
"Of course, I do," Ragland responded.
As the conversation continued, he grew suspicious. "Let me ask you a question: You're not setting me up, are you?" he asked.
But the woman kept her cool, and the conversation left police "with what we really needed," Evans said.
Ragland was arrested and charged with murder. The prosecution's star witness at his trial was this ex- girlfriend. The key evidence? The airport recording.
The defense fought hard to attack the ex-girlfriend's credibility, questioning why she stayed with Ragland for about a year after his confession. His lawyer also questioned just how incriminating that airport recording was since he never directly admitted to killing DiGiuro.
Ragland was found guilty of intentional murder and sentenced to 30 years in prison. But several years later, his conviction was overturned, and he pleaded guilty to second-degree manslaughter instead, serving up to five years in prison.
Tune into Dateline this Friday at 10 p.m. ET/9 p.m. CT to find out why.