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.
Swedish police then became aware of the arrest of Joseph James DeAngelo – the so-called “Golden State Killer” – using genetic information from the commercial genealogy website GEDmatch. In this notorious case, police compared genetic material left at the crime scene to the DNA of people who voluntarily submitted their gene information to public genealogy databases to trace their own family tree. This was able to identify a number of DeAngelo’s family members, eventually leading them to DeAngelo himself. After following the suspect, they then picked up an unidentified object he discarded to obtain his DNA, which then linked him to a number of the crimes. The novel method proved to be a remarkable success; DeAngelo will spend the rest of his life behind bars.
Intrigued by the story, Swedish police asked higher authorities whether they could solve the Linköping murders using this DNA-based genealogy method in a pilot study. They eventually got the green light in 2019, and a new investigation got underway.
Sifting through data on the platforms GEDmatch and FamilyTree, investigators found a number of distant relatives to the DNA picked up from the crime scene. A further investigation used this lead to identify two prime suspects: two brothers. More snooping revealed one of the brothers had a direct match to the crime scene DNA, affirming his guilt.
The man was put on trial in 2020 and was convicted of the crime. According to local media reports, his name is Daniel Nyqvist, a Swedish man who killed the pair in an unprovoked attack while "under the influence of a severe psychological disorder."
Writing in a new study, published in the journal Forensic Science International: Genetics, researchers detail how the puzzle was put together in the hopes of inspiring investigators to crack other cold cases. As they explain, this method has been used for a growing number of crime cases, but it’s never been formally described for future reference.
"We want to tell others about the problems that we faced when working with this pilot case, and how we dealt with them. We can prevent others reinventing the wheel, and make sure that the knowledge available is extended and improved", Andreas Tillmar, lead study author and adjunct senior lecturer in forensic genetics at the Department of Biomedical and Clinical Sciences at Linköping University, said in a statement.
The researchers also explain that the method, although extremely useful, is still riddled with legal and ethical dilemmas. First and foremost, many people using commercial genealogy platforms to learn about their family tree are unaware their genetic data and kinship relationships are openly available to authorities. However, if this data helps to bring murderers to justice, do the ends justify the means?
“There is a risk of a conflict between that two important principles: the right of the individual to privacy against the aspiration of society to solve serious crime", adds Tillmar.
"It's a grey area. Technology is often one step ahead of the law.”