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Public DNA Database Cracked the Golden State Killer Case, Police Say

Authorities were led to Joseph James DeAngelo by cross-checking his genetic data on GEDmatch, a free and open-source DNA database.
A photo of accused rapist and killer Joseph James DeAngelo is displayed during a news conference on April 25, 2018 in Sacramento, California. Image: Justin Sullivan/Getty Images

The elusive Golden State Killer, also known as the East Area Rapist and the Original Night Stalker—a serial murderer who terrorized California during the 1970s and 1980s—was given another alleged name this week: 72-year-old Joseph James DeAngelo.

Authorities arrested DeAngelo, a former police officer, in connection to the 1978 murders of Brian and Katie Maggiore. DeAngelo is suspected of 12 homicides, including the Maggiore killings, at least 45 rapes, and 120 home burglaries.


It was novel DNA techniques—a free, open-source genealogy website called GEDmatch—that led authorities to the Sacramento man. Using DNA evidence from old crime scenes, Contra Costa County investigators uploaded his genetic profile to GEDmatch, which lets people publicly share DNA data. There, they located DeAngelo’s relative, who police say had a family member matching the killer’s profile.

Police lurking on genealogy sites to solve crimes is becoming more common, but is still highly controversial.

According to the Bay Area’s Mercury News, which first reported the database that authorities used:

Lead investigator Paul Holes, a cold case expert and retired Contra Costa County District Attorney inspector, said his team’s biggest tool was GEDmatch, a Florida-based website that pools raw genetic profiles that people share publicly. No court order was needed to access that site’s large database of genetic blueprints. Other major private DNA ancestral sites said they were not approached by police for this case.

“We found a person that was the right age and lived in this area—and that was Mr. DeAngelo,” Steve Grippi, the assistant chief for the Sacramento County District Attorney, told The New York Times.

Police confirmed the connection by obtaining “abandoned” DNA samples from DeAngelo. It matched the evidence of more than 10 murders in California.

GEDmatch did not immediately respond to a request for comment.


Other popular genealogy sites like 23andMe and do not allow law enforcement to access their data without a court order.

“The answer is no, we have not received inquiries regarding this case,” a 23andMe spokesperson told Motherboard, noting that the service doesn’t allow the comparison of 23andMe data with third-party data, even for forensic use.

“Broadly speaking it's our policy to resist any law enforcement inquiries with all legal and practical means at our disposal,” the 23andMe rep said. “We have had a handful of inquiries over the years, and have never given customer information to law enforcement officials.” denied involvement as well. “We have not been in contact with law enforcement regarding the Joseph James DeAngelo case,” a spokesperson for the company told Motherboard. “Ancestry advocates for its members’ privacy and will not share any information with law enforcement unless compelled to by valid legal process.”

MyHeritage, which lets users upload their raw DNA data, also denied involvement.

GEDmatch was founded in 2010 by Curtis Rogers and John Olson, and is based out of Florida. It was created as a tool for “amateur and professional researchers and genealogists,” according to the site. By uploading your data to GEDmatch, you can find people who share common DNA, based on genetic markers, and calculate your connection to them.

GEDmatch doesn’t do DNA testing, it only aggregates existing results from sites like 23andMe. As Ars Technica noted, the database didn’t even require a login when it was launched. Its privacy policy currently states that “users participating in this site should expect that their information will be shared with other users.”


“While the database was created for genealogical research, it is important that GEDmatch participants understand the possible uses of their DNA, including identification of relatives that have committed crimes or were victims of crimes,” GEDmatch said in a statement posted on the site.

Other sites, like YHRD and YSearch, also permit users to similarly share their DNA data.

While California’s “Grim Sleeper” and “Roaming Rapist,” two other violent criminals, were caught this way, in 2010 and 2012 respectively, innocent people have also been wrongfully accused in the past based on information harvested from DNA databases.

In March 2017, investigators in Oregon’s Clackamas County misidentified an elderly resident, who remains unnamed, as a suspect.

According to court records obtained by The Associated Press, investigators similarly compared crime scene DNA to public genetic profiles on DNA databases, and used that information to identify the Oregon man. The man shared a “rare genetic marker” with the Golden State Killer, investigators said, which convinced a judge to order a DNA sample from him.

In California, police are required to collect DNA samples from everyone arrested for a felony, without a judge’s review, and when criminal charges are not pressed.

DeAngelo was arraigned today in Sacramento County Superior Court on two counts of murder, and was denied bail.

This story has been updated to include information about Clackamas County, Oregon, misidentifying an elderly man as the Golden State Killer, and DeAngelo's arraignment today.

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