DNA sleuthing helped crack a decades-old cold case, leading to the arrest of a man suspected of being the Golden State Killer. Could the same type of detective work on genealogy websites be used to catch another of California’s most infamous and elusive criminals—the Zodiac Killer?
“It is possible,” said Pam Hofsass, a former San Francisco homicide detective who worked on the Zodiac case and now runs the forensic lab for the Contra Costa County Sheriff’s Office.
The Zodiac Killer roamed northern California from December 1968 through October 1969, but was never caught despite at least one close run-in with police. He is known to have attacked seven victims, killing five and leaving two survivors. However, the Zodiac claimed responsibility for many more deaths in letters, often signed with a symbol of a cross over a circle.
Like the Golden State Killer, the Zodiac Killer took on an almost mythological presence in the psyche of Californians; the story of his killing spree has been told in multiple books and movies over the decades.
Hofsass said one of the biggest hurdles to using DNA to track the Zodiac Killer is getting a clean genetic sample. She said evidence collection rules were much looser on crime scenes during the era when the Zodiac was active because DNA forensic science didn’t exist. Multiple people would often handle evidence without gloves, adding their own genetic material to collected objects.
She gave an example of a blood-soaked glove she found when she first started working on the Zodiac case around 2009. The blood on the outside of the glove was identified as that of the Zodiac’s last known victim, Paul Stine, a San Francisco cab driver shot in the head in the Presidio neighborhood in 1969, Hofsass said. But the blood and other matter collected from inside the glove was too muddled to be of use.
Tom Voight, a recreational Zodiac expert who runs the website zodiackiller.com , said he believes a clean DNA sample could be taken from saliva that might be on envelopes mailed by the Zodiac. The serial killer was a prolific communicator, sending letters, cards and mysterious cyphers to media, law enforcement and others, including former Sacramento Bee reporter Paul Avery while he worked at the San Francisco Chronicle.
“I think Zodiac was definitely licking his own stamps and envelopes,” Voight said. “You just need to get the evidence, get it to the lab. Just copy what was done with the Golden State Killer.”
Hofsass agreed that the envelopes could be useful. “I think they are worth re-examining,” she said. “That would go for all of the [law enforcement] agencies that received mail [and] taunting cards.”
That approach was attempted in 2002 when ABC’s Primetime asked a forensic expert from the San Francisco Police Department to compare a partial DNA sample authorities had from the surface of a stamp of a Zodiac letter with the DNA profiles of three men who were rumored suspects. That DNA analysis eliminated all three as suspects due to their significant differences with the sample. What was on the stamp provided only a partial genetic profile and wasn’t strong enough to identify the killer, Voight said.
But technology and techniques have improved. Golden State Killer suspect Joseph James DeAngelo was identified when DNA saved from an old crime scene was associated with a distant relative on GEDmatch, an open-source genealogy site. Until recently, law enforcement limited DNA searches to databases of those with a criminal history. The use of the commercial site allowed investigators to virtually canvas a new pool of possible suspects, which included relatives of the killer.
From that hit, investigators from a federal and state task force tracked his family tree to narrow it down to men who lived in the vicinity of the crimes, eventually targeting DeAngelo in April.
Voight said he would like to see a similar joint-agency effort around the Zodiac Killer.
“If California law enforcement authorities would simply join forces as they did with the Golden State Killer … then this would be a pretty big year because I don’t think it would take very long to catch him.”