Mei Leung, 9, was raped and murdered in 1984 in her apartment building. Just two weeks ago, police made a shocking announcement. They said a DNA hit linked her death to the notorious "Night Stalker" Richard Ramirez, who was convicted in 1989 of 13 murders.
Assistant District Attorney Braden Woods heads San Francisco's cold case unit.
"I've reviewed over a hundred cases over a year and a half that we've had this unit. Homicides, sexual assaults, residential burglaries," says Woods.
Cases like the 1991 rape murder of Karen Wong. In 2008, nearly two decades later, a convicted burglar was charged with her rape and murder. DNA evidence preserved from the crime scene linked him to Wong's death.
Jenny Read was raped and stabbed to death in 1976. Last year, more than three decades later, church deacon James Lee Mayfield was charged with her murder. Again, it was because of a DNA match.
The team that investigates cold cases meets every Monday to discuss new cases and review the progress of old ones.
"We're probably looking at somewhere in the area probably 37 good open ones right now
In the room are the lieutenants from burglary, homicide and sex crimes, and the medical examiner and crime lab manager. The captain of investigations leads the meetings. Joe Toomey and Holly Pera are also there -- the two homicide inspectors assigned full-time to the cold case team.
"We bounce cases against each other. By meeting every Monday and discussing it we usually come to a fair resolution about which cases we should give priority to," says Woods.
"I think it's going to lead to real justice for victims," says San Francisco District Attorney Kamala Harris, who created the cold case unit with $400,000 of federal funding in 2006. She says "When they committed that crime, way back when, they think they got away with it. And they're more likely to do it again and we want to remove these perpetrators from the streets."
Toomey and Pera are veteran homicide inspectors who have been partners for more than a decade. They say a DNA hit is not enough to take the case to court. The inspectors have to painstakingly reconstruct the case and find more evidence.
"I think cold cases are more difficult than the warm cases because it's more difficult to find witnesses after all these years. It's more difficult to establish someone's sense of their memory after all these years," says Pera.
"Cases that are particularly difficult are when you're trying to find witnesses that were or are women because they change their names. They have married names, maybe married a couple of times or whatever," says Toomey.
For families of victims, solving their case can be bittersweet. While it may give them a sense of closure, it also brings back a flood of emotions.
"What people seem to be the most appreciative of is the fact that we even re-looked at it at all. The results are fantastic, that's the frosting on the cake, but the fact that we were even able to look at it at all just means the world to these people," says Pera.
And to other families who are still waiting, each cold case solved by those in the unit means there is hope for them.