The DNA of Swedish inventor Peter Madsen, who is accused of killing and dismembering journalist Kim Wall, will be checked against a string of cold cases.
Swedish police announced they would reopen unsolved killings to test against Madsen’s DNA, and Norwegian authorities will also request a sample.
According to The Independent, Norway's National Criminal Investigation Service said it was standard procedure.
In Denmark, cold-cases are also being reexamined, including the death and dismemberment of a 22-year-old Japanese tourist. The tourist’s body was discovered in Copenhagen harbour in 1986.
Last week, a court heard that Madsen had video footage showing women being violently killed on his computer.
Prosecutor Jakob Buch-Jepsen told a Copenhagen court that officers had found images "which we presume to be real" of women being strangled and beheaded on his computer, the ABC reports. Authorities do not believe Madsen is responsible for filming the videos.
Inventor and submarine owner Madsen claimed that the computer was not his and was used by a number of staff at his Copenhagen workshop.
Prosecutors revealed that an ongoing post-mortem found the journalist had been stabbed 15 times, although her exact cause of death is yet to be determined. The court also heard that DNA matching Wall’s was found under Madsen’s fingernails.
Madsen has claimed Wall died accidentally, saying she was hit by a hatch cover on his submarine.
"I lose my foothold and the hatch shuts," the inventor told the Copenhagen court last month. He said the journalist was then knocked on the ground.
"There was a pool of blood where she had landed."
Asked why he threw Ms Wall overboard, Madsen told the court: “"In the shock I was in, it was the right thing to do,” the BBC reports.
Ms Wall disappeared after she boarded Mr Madsen’s home-made submarine on August 10. Ms Wall's boyfriend alerted police when the reporter didn't arrive home, after boarding the ship for what was supposed to be just a few hours for a story.
Police identified the torso of a woman they found on August 21 in Danish waters, south of Copenhagen, as Ms Wall.
The body was missing its head, arms and legs.
The court ordered that Mr Madsen undertake a psychiatric evaluation and that he be kept in custody for four weeks.