Double murder in Sweden solved 16 years later thanks to genealogy websites


The mystery of the 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, Swedish scientists say this is the first time the technology has been used to catch a murderer outside the United States.

On October 19, 2004, an eight-year-old boy was stabbed to death while walking to school in the town of Linköping, southern Sweden. The perpetrator then turned to a 56-year-old woman who had just left her home and who had witnessed the event, repeatedly stabbing her and leaving her for dead. The assailant fled but left behind a knitted hat and the butterfly knife he used to kill the victims. Although traces of DNA from the murder were drawn on the gun, detectives ran out of leads and the investigation dried up.

Swedish police then learned 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 DNA from people who voluntarily submitted their genetic information to public genealogical databases to trace their own family trees. This identified a number of DeAngelo’s family members, ultimately leading them to DeAngelo himself. After following the suspect, they then picked up an unidentified object which he threw away to obtain his DNA, which in turn linked him to a number of crimes. The new method has proven to be a remarkable success; DeAngelo will spend the rest of his life behind bars.

Intrigued by the story, Swedish police asked higher authorities if they could solve the Linköping murders using this DNA-based genealogy method in a pilot study. They finally got the green light in 2019 and a new investigation was launched.

Sifting through data on the GEDmatch and FamilyTree platforms, investigators found a number of distant relatives whose DNA was collected at the crime scene. Further investigation used this lead to identify two main suspects: two brothers. More espionage revealed that one of the brothers had a direct match with DNA from the crime scene, claiming his guilt.

The man was tried in 2020 and was found guilty of the crime. According to local media reports, his name is Daniel Nyqvist, a Swede who killed the couple in an unprovoked attack while “under the influence of a serious psychological disorder”.

Writing of a new study, published in the journal Forensic Science International: Genetics, the researchers detail how the puzzle was put together in hopes of prompting investigators to solve other cold cases. As they explain, this method has been used for an increasing number of criminal cases, but it has never been formally described for future reference.

“We want to tell others about the issues we faced while working on this pilot case and how we handled them. We can prevent others from reinventing the wheel and ensure that the knowledge available is expanded and improved, ”Andreas Tillmar, study lead author and associate lecturer in forensic genetics in the Department of Biomedical and Clinical Sciences at the ‘Linköping University said in a declaration.

The researchers also explain that the method, while extremely useful, is still fraught with legal and ethical dilemmas. First and foremost, many people who use commercial genealogy platforms to learn more about their family tree are unaware that their genetic data and family relationships are openly available to authorities. However, if this data helps bring murderers to justice, does the end justify the means?

“There is a risk of conflict between these two important principles: the right of the individual to privacy versus the aspiration of society to solve serious crimes,” adds Tillmar.

“It’s a gray area. Technology is often one step ahead of the law.”


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