Authorities say Joseph DeAngelo was arrested after a lengthy process of comparing crime-scene DNA to genetic information via the genealogical site GEDmatch
The “innovative DNA technology” that authorities say helped them catch California’s notorious Golden State Killer has been revealed as a lengthy process of comparing the murderer’s DNA — found at one of the crime scenes — to genetic profiles that are publicly available via a genealogical website, PEOPLE confirms.
The crime scene DNA sample matched that of one of Joseph DeAngelo’s relatives, according to the Sacramento Bee, who first reported news of how DeAngelo was connected to the Golden State Killer case after so many years. (Prosecutors confirmed the Bee‘s reporting to PEOPLE but declined further comment.)
The site confirmed its involvement in a Friday statement.
“Although we were not approached by law enforcement or anyone else about this case or about the DNA, it has always been GEDmatch’s policy to inform users that the database could be used for other uses,” the company said, in part.
DeAngelo, a 72-year-old former police officer and retired mechanic living in Citrus Heights, California, is charged with murder in eight slayings linked to the Golden State Killer, who has also been known as the East Area Rapist and the Original Night Stalker.
Police say DeAngelo, who was arrested on April 24, is suspected of killing at least four more people but charges have not yet been filed.
He remains in custody and is scheduled to return to court on May 14, jail records show. It is unclear if he has pleaded to his charges. His attorney declined to comment to PEOPLE on Tuesday.
“We have the law to suggest that he is innocent until he’s proven guilty and that’s what I’m going to ask everyone to remember,” she said Friday, after DeAngelo’s initial court appearance, according to the Associated Press. “I feel like he’s been tried in the press already.”
From 1976 to 1986, according to authorities, the Golden State Killer committed 12 murders, 45 sexual assaults and more than 120 burglaries across California — one of the longest and most vicious crime sprees in U.S. history.
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How Suspect Was Caught
An investigator on the case told the Bee that he created an “undercover profile” on GEDmatch and then was able to match DNA from one of the Golden State Killer’s crime scenes to a relative of DeAngelo’s whose DNA information was on the website.
From there law enforcement pieced together a broader family tree of relatives connected to the DNA match, using available information such as names and emails as leads for more digging, as well as other clues, according to the AP and the Bee.
Authorities honed in on DeAngelo based on his age and where he lived, among other factors, Sacramento County District Attorney Anne Marie Schubert told ABC News.
They then put DeAngelo under surveillance long enough to obtain his “discarded DNA,” which they say is a match with the killer’s.
“If it wasn’t for that DNA, his name would never have surfaced — period,” Schubert told PEOPLE after DeAngelo was arrested. “There was a needle in that haystack, and we found that damn needle. I always believed it was a matter of persistence.”
A similar process led authorities to a previous misidentification in the case, according to the AP: Last year they believed a 73-year-old man in Oregon was a possible suspect, based on genetic information he shared with the killer.
The unconventional techniques that led to DeAngelo’s capture last week have brought scrutiny to the privacy rules around GEDmatch and other genealogy research websites, raising concerns about how people’s DNA information may be used by law enforcement in the future.
“It’s not only users that are caught up in this net, it’s also those with relationships to users,” one outside researcher told the Associated Press. “In this case, though, it’s not just networked relationships, it’s actual genetic relationship.”
“A success like this gets trumpeted in headlines all over America,” the ACLU’s Jay Stanley told the Bee. “But for every success like this, how many people are having their lives put under the microscope of law enforcement … because a relative uploaded their DNA?”
Unlike online companies such as Ancestry.com, however, GEDmatch is free and “open-source,” allowing its users to upload the DNA information they obtained from other sites (such as Ancestry) into GEDmatch’s database in order to look for matches with other people.
Essentially, anyone who uses GEDmatch has voluntarily given up the privacy of their data by submitting it into a larger database that is searchable by others. (GEDmatch said it does not make the actual DNA viewable, only information such as matches and other “manipulations of the data.”)
ABC News reports that Ancestry and similar companies do not typically make their DNA information available to authorities.
“As a private platform, we do not allow the comparison of genetic data processed by any third party to genetic profiles within our database,” a spokesman for the DNA-testing site 23andMe told the AP. “Further, we do not share customer data with any public databases or with entities that may increase the risk of law enforcement access.”