Genetic material from genealogy websites helped bring police a step closer to the man they believe is the Golden State Killer, the Sacramento District Attorney's office said.
Chief Deputy District Attorney Steve Grippi confirmed the news, first reported by the Sacramento Bee, that police matched crime scene DNA to genetic material from a relative who was registered on genealogy sites.
Grippi told the newspaper that investigators spent a long period of time exploring online family trees before focusing the investigation on a suspect. He told CNN that other details in the Bee report are "accurate."
Shaun Hampton, a Sacramento County Sheriff's department spokesman, also told CNN that investigators used sites that collect DNA information.
Joseph James DeAngelo, 72, was arrested Tuesday in a Sacramento suburb. He is accused of being the man who killed 12 people and raped more than 50 women in the 1970s and 1980s.
"It is fitting that today is National DNA Day," Sacramento District Attorney Anne Marie Schubert told reporters Wednesday. "We found the needle in the haystack and it was right here in Sacramento."
While it's unclear what DNA service was used, four companies contacted by CNN denied having any connection to the case.
Ancestry, Vitagene, MyHeritage and 23andMe said they didn't provide customer information to law enforcement officials.
Companies allow customers to take an at-home test and then send in their DNA. Scientists then compare the DNA to those they already have on record in hopes of connecting them with unknown branches of their family tree.
How DNA has changed the case
DNA played a key role in DeAngelo's arrest and has been changing the course of the investigation for decades.
Detectives believed the homicides in Sacramento and Southern California were connected but they could not prove it.
"But he would not leave fingerprints, so we could not prove, other than his M.O., that he was the same person. We did not know anything about DNA," said Larry Crompton, retired detective for Contra Costa County Sheriff's Department.
Once DNA tests were available, investigators were able to confirm the same man committed three of the attacks, according to Paul Holes, who investigated the case for the Contra Costa County District Attorney's Office.
In 2001, DNA evidence determined the East Area Rapist was the same offender as the Original Night Stalker. Now, the man is known as the Golden State Killer.
When DeAngelo's name emerged in connection with the case last week, detectives matched a discarded DNA sample to evidence from the investigation, law enforcement officials said Wednesday.
California's controversial DNA database law
Bruce Harrington constantly pushed California officials to use DNA testing, hoping it would help catch the man who killed his brother and sister-in-law nearly 40 years ago.
As police announced the arrest of the Golden State Killer, Harrington had a simple message for those who opposed attempts to expand the California's criminal offender DNA database.
"You were wrong," he said.
Critics and some state officials had cited the privacy rights of people in police custody and questioned the constitutionality of allowing the state to gather DNA samples without evidence of guilt.
Harrington spent years in front of public safety committees until California voters passed Proposition 69, known as the "DNA Fingerprint, Unsolved Crime and Innocence Protection Act," in 2004.
The proposition gave the state broader powers to collect DNA. Now, it could get samples from anyone not just convicted of a felony, but even arrested for one.
In some cases, authorities could also collect DNA from misdemeanor arrests.
The use of DNA technology in DeAngelo's arrest highlights the progress that law enforcement agencies in California have done in their use of forensic science.
"I began my quest in the mid 90s. It was 15 years until we heard that there was a DNA sample taken from our scene," Harrington said at a press conference Wednesday.
Note: Unless stated otherwise, the interviews from this story came from the HLN series "Unmasking A Killer."