DNA tests can reveal more than your Irish roots. Online genealogy sites such as 23andme.com and Ancestry.com offer to trace your ancestral heritage but can reveal a lot more than that. Customers who submit their DNA for testing have found their lives changes, families splintered and everything from an unknown sibling to a potential wrongdoer in the family, like the recent case of Joseph DeAngelo, who committed a series of heinous offenses across the state of California.

When Joseph James DeAngelo was arrested in late April, it was thanks to the DNA banked at the website GEDMatch. One of DeAngelo’s family members had used a geneaology website and, when authorities ran evidence from unsolved crimes through a larger open-source database, they found a match for “50 confirmed [sexual assaults] and 12 homicides over a 10-county area in California between 1974 and 1986.” That person was Joseph DeAngelo.

The so-called Golden State Killer struck throughout California, starting in Sacramento and East Bay before moving south to Santa Barbara and Orange County. As DeAngelo moved around California, his crimes led to the emergence of several theorized offenders, including the East Area Rapist, the Original Night Stalker, and the Visalia Ransacker, in addition to the Golden State Killer. During his run of crimes, police speculated that the suspect could be a cop because he was able to elude capture for so long. They were right. Joseph DeAngelo worked for the Auburn Police Department near Sacramento for three years.