SAN JOSE, Calif. (KTVU) - Santa Clara County sheriff Laurie Smith says she's cross-checking all of her cold cases using DNA evidence to see if there's a link to Joseph James DeAngelo -- the so-called Golden State Killer.
Other law agencies in the South Bay are doing the same, saying this high-tech way to gather evidence is a reliable path to justice.
For 18 years, Santa Clara police officer Brian Lee has been a leading force in solving crimes. As a trained crime scene investigator, or CSI, Lee says the painstaking processes employed on each case can form an iron-clad ring of protection around crucial evidence.
"I've encountered several cases where evidence that I've collected identified a suspect years down the road," said Lee, who provided KTVU with exclusive access to the Santa Clara police CSI lab.
Beyond laser guided schematics of a crime scene, Lee says all DNA evidence is meticulously collected, labeled, and triple sealed in envelopes. Then it's stored in a refrigeration unit inside a secure evidence room that even he can't access without authorization.
"It insures that there's no cross-contamination and that there is no chance of cross-contamination, or any kind of contamination, with the DNA we are collecting," said Lee.
The issue of collection and contamination could become a central strategy for Joseph James DeAngelo’s defense lawyers, who's been arrested and charged in the cadre of crimes that occurred from 1976-1986.
"When it comes to a cold-case, DNA is a prosecutor's best friend," said attorney Steven Clark.
A former prosecutor and now a legal analyst, Clark says DNA collected from the scene linked DeAngelo enough for him to be charged. But the evidence collection process must be pristine, or the case could suffer.
"What the defense is going to do now is see if this is truly a DNA match. ‘Is the DNA reliable? Is there enough to connect Mr. DeAngelo to these crimes?’” said Clark. “But there also going to look at is there some innocent explanation to why his DNA was at the crime scene.”
The strength, or weakness of those queries depends on how well CSI investigators did their jobs many years ago, and if that work will stand up under the spotlight of prosecution and defense.
"The DNA is very important but the prosecution will still need to build a case. The DNA evidence will be at the forefront of the case," said Clark.
The next step for prosecutors is to reverse engineer the crimes, go back and re-interview witnesses to bolster their case. Experts say it could take many months before a possible trial begins.