The mystery of 16-year-old double murder in Sweden was solved last year using data from genealogy websites, a method first used to identify and capture the “Golden State Killer” in 2018. Detailing the case in a new study, scientists in Sweden say it’s the first time this technology has been used to catch a murderer outside the US. On October 19, 2004, an eight-year-old boy was stabbed to death while walking to school in the city of Linköping in southern Sweden. The attacker then turned on a 56-year-old woman who had just left her home and witnessed the event, stabbing her several times and leaving her for dead. The attacker fled the scene but left behind a knitted cap and the butterfly knife he used to kill the victims. Although traces of the murder’s DNA had been traced on the weapon, detectives ran out of leads and the investigation dried up.