SACRAMENTO, Calif. — The break that authorities said led them to the man accused of being the Golden State Killer came when they linked DNA evidence from the slayings to genetic information contained on a consumer genealogical website, authorities said Thursday.

Investigators knew the killer only through a string of DNA recorded in several of the dozen murder scenes. Shaun Hampton, a spokesman for the Sacramento County Sheriff’s Department, said officials had struggled for years to figure out who that DNA belonged to. Recently, they tapped genealogical databases that the public uses to search for relatives and ancestors, he said.

JOSEPH JAMES DEANGELO

Law enforcement sources told the Los Angeles Times that information from those websites dramatically reduced the size of their search. Eventually they narrowed the investigation to several families listed in the database, with a pool of about 100 men who fit the age profile of the killer, said the sources, who spoke on condition of anonymity.

Hampton declined to name the site used or provide details about exactly how authorities made the match.

The trail eventually led them to Joseph James DeAngelo, a 72-year-old former police officer living in Citrus Heights, a suburb of Sacramento. The sources said the detectives then retraced his life, looking for connections between the numerous crimes across California and where he was during those times.

Private companies that provide ancestry searches from DNA samples submitted by paying participants usually also guarantee privacy for their users. However, customers are alerted to potential matches and can use the service to connect with possible relatives. Sacramento County district attorney’s spokeswoman Shelly Orio said more details about the DNA evidence would be laid out Friday during a court hearing.

Several popular DNA sites – Ancestry.com, 23andme and MyHeritage – all denied that law enforcement officials formally reached out to them about the Golden State Killer.