A free, open-source genealogy site had no clue investigators were using its services to track down suspected Golden State Killer Joseph James DeAngelo, who is accused of slaying at least 12 people and raping dozens of women in California in the 1970s and 1980s. The site, called GEDmatch, has a database of DNA profiles that users have uploaded and shared publicly. Using the website, investigators in the Golden State Killer case were able to link crime-scene DNA to one of DeAngelo’s distant relatives, authorities said. The New York Times reported Friday that authorities “created a fake profile and pseudonym” on the site several months ago in order to access it. “This was done without our knowledge, and it’s been overwhelming,” GEDmatch co-owner Curtis Rogers told Mercury News. While authorities do not need a court order to access genealogy data, civil liberties advocates were alarmed by the revelation. “People who submit DNA for ancestors testing are unwittingly becoming genetic informants on their innocent family,” said Steve Mercer, a chief attorney at the Maryland Office of the Public Defender’s forensic division. DeAngelo, a 72-year-old retired mechanic and former police officer will be arraigned in court on Friday and was arrested Tuesday in Sacramento, as reported by The Daily Beast.