On New Year's Eve 2006 the Broncos season ended in a crushing overtime loss that eliminated them from the playoffs. Melancholy settled over Denver, but the worst was yet to come.
In the early morning hours of New Year's Day, Broncos cornerback Darrent Williams was murdered in a drive-by shooting.
The 24-year-old's violent death rocked the world of sports and became a turning point for the Denver Police Department.
A CBS News analysis found the department solved only 17% of the city's homicides in 2006. Two years later, that number jumped to 93%.
CBS News Colorado reporter Shaun Boyd asked former Denver District Attorney Mitch Morrissey this month what happened.
"Well, we changed a lot of things," he said.
The changes included the creation of a witness protection program in the DA's office and an undercover fugitive unit at DPD.
Williams' killer was part of a street gang that instilled fear in would-be witnesses.
"The back of Darrent Williams' funeral home where they were holding the service were gang members wearing 'Stop the Snitching' T-shirts. ... That yields a difficult environment to solve cases," said Steve Siegel, who spearheaded the witness protection program.
"They were building little piece by little piece a sense of trust that then gets passed word by word, mouth by mouth, family to family, neighbor to neighbor that you can talk to these people. You can trust them."
It was trust that was reinforced by a new cold case unit at DPD.
"The cases that go unsolved? We don't give up. We're not going to give up on those cases. We're not going to flip the calendar and move on to the next set of challenges," said Denver Police Chief Paul Pazen.
Despite being down 100 officers, the Denver Police Department today has three detectives dedicated to cold cases. Pazen traces that commitment back to a meeting he attended many years ago where families of homicide victims and missing persons took turns telling their stories.
"You could still see the pain and the hurt moreso on the unsolved cases. And it was just one of those moments that I have never forgotten that I have never forgotten," Pazen said. "It reinforced what our major crimes detectives do on a daily basis: that we have to solve these cases.
The dedication isn't lost on families, many of whom send cards and letters that detectives like Adam Golden keep at their desks, along with victim's pictures and funeral notices. He said it's a good reminder of why the investigator's job is so important.
"This is one from a mother of a homicide victim," Golden said, showing one card he received and felt a great boost from. "She sent me this card talking about the worst day of her life and how hard it must be for me."
"It is more than a job. It is something that we live and we breathe. We take it home with us," he said.
Commander Matt Clark oversees Denver's homicide and cold case units and told CBS News Colorado they invest heavily in their investigators.
"It's tough to get them to go home sometimes, after 'Hey you've been here 24 hours, you've got to get offline,'" Clark said.
Clark says the extensive training members of his team gets includes things like "open source intelligence."
"We work with social media platforms. We do shooting reconstruction schools, homicide schools."
They also partner closely with federal law enforcement.
"I have an ATF agent who's embedded in the homicide unit. He sits at a desk in the unit. And the resources he can bring to us are significant.
The year after Williams' murder Denver voters also approved a $28 million state-of-the-art crime lab.
"I saw DNA (work) that was done in some cases in 24 hours if the chief asked for it," Morrissey said. "So they could bring that to bear, and there's nowhere in the country where you see that."
Denver's approach to solving homicides has caught the attention of the National Institute of Justice.
"They called what we had the triangle of collaboration. It was the detectives, the DA's office and the crime lab."
The city's homicide rate is the highest in more than 30 years with 2 people killed -- on average -- every week. Clark says they have solved about 70% of those murders so far this year and last year, but he's focused on the ones that are unsolved.
"I recognize that there's 25% of our cases that aren't (solved). There's 10 families that are waiting for that closure."
Closure was finally reached for Williams' family three years after his death. His killer got a life sentence.
"Sometimes it's luck. But a lot of times your luck comes when you build the right teams, when you have the protocols in place. And we did all of that," Morrissey said.
"I hope it communicates to the offenders that the Denver Police Department is still looking for the offenders. That we're coming after you and you won't get away with murder," Clark said.
Complete coverage of "Crime Without Punishment' from our CBS stations across the country and CBS News.