Even as the trial begins, Mixsell and Gagnon are still investigating Mezquia, and they're now convinced he never met Mia Zapata until the night of her murder.
"He was always looking for a victim," says Gagnon. "He was a predator."
They've also discovered Mezquia has a record of assaulting women, including his wife. But the heart of the case against Mezquia is a tiny bit of saliva that was swabbed from Mia's breast. Cold Case prosecutor Tim Bradshaw tells jurors that the saliva, and the DNA it carries, is all the evidence they need.
"The evidence that was previously left in darkness has been illuminated and exposed to the light of the laboratory and will be exposed for your consideration in the light of this courtroom," says Bradshaw.
Mezquia, a Cuban, listens to the trial through translators, but he never speaks and never takes the stand in his own defense.
His attorneys try desperately to argue that the presence of his saliva does not prove he either raped or killed Mia. They also try to argue that the DNA was corrupted at the crime scene, that the DNA was somehow ruined by paramedics trying to revive Mia, and that Mezquia's DNA may not have originally been on Mia's breasts.
Mercifully, the trial concludes after just eight days, and the detectives and Dick Zapata are confident of victory. "I can't see 12 people walking this guy. I mean that would probably be the biggest travesty of my career," says Gagnon.
The jury does something completely unexpected. They deliberate for three days, and tensions start running high. Then, on the fourth day, the jury reaches a verdict for Mezquia.
After wrestling for days with microscopic evidence that is 10 years old, the jury convicts Mezquia. His punishment is severe: Mezquia will serve 37 years in prison, well above the state's normal sentence for first-degree murder.
"I think justice is served," adds Gagnon. "We got the right verdict."
And with the Mia Zapata case now finally put to rest, the Seattle Cold Case Squad has a message for anyone out there who thinks they got away with murder.
"The clock's always ticking. You're not a free man," says Gagnon. "Maybe someday on the road, there'll be a knock on the door. If you're having trouble sleeping at night, I think we've done our job."