Golden State Killer case opens possibility of using DNA in other notorious cold cases

LOS ANGELES -- It was an unconventional approach that landed Joseph DeAngelo in court decades after his alleged spree of murders and rapes. Investigators entered evidence from the Golden State Killer's cases into a genealogical database, and through links with several distant relatives, got a full DNA profile that matched DeAngelo.

Now, that same technology could help solve some of California's most notorious cold cases, including the infamous Zodiac Killer murders.

Arraignment Held For Alleged "Golden State Killer" Joseph DeAngelo Jr

Joseph James DeAngelo, the suspected "Golden State Killer," appears in court for his arraignment on April 27, 2018 in Sacramento, California. 

Justin Sullivan/Getty Images

"It will break break it wide open," said Det. Jim Jacksch.

Jacksch has spent most of his career on the Zodiak task force, hunting the man who, 50 years ago, terrorized northern California. The Zodiac Killer boasted about killing as many as 37 people, and taunted police by sending them cryptic letters.

"It's real big. it's a great place for an investigation to really start," said Jacksch.

Now, investigators are trying to recover DNA from saliva on the stamps from those very letters. According to DNA expert Monte Miller, using genealogy sites gives them a potent new weapon.

"Anytime we can't identify the criminal, if we could identify some of the criminals relatives, it will give us a very good leg up on solving some of these crimes," said Miller. 

It's giving new hope for cracking cases that had long gone cold and seemed like they might never be solved.

Detectives plan to enter the DNA results from the Zodiac letters into the same database that helped track down the alleged Golden State Killer. If they're successful, this could finally bring some closure for relatives of the Zodiac Killer's victims.