COPENHAGEN, Denmark -- Danish police say divers have recovered a saw from the sea off Copenhagen and forensic investigators are checking whether it was used to dismember the body of a Swedish journalist.

Copenhagen police investigator Jens Moeller Jensen said Thursday they were still searching for the arms of 30-year-old Kim Wall.

This photo shows allegedly Swedish journalist Kim Wall standing in the tower of the private submarine "UC3 Nautilus" on August 10, 2017 in Copenhagen Harbor. Getty

Wall's torso was found on a southern Copenhagen coast Aug. 21, and her decapitated head, legs and clothes were found at sea last week.

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Wall was last seen on a home-made submarine with inventor Peter Madsen, who is being held in custody. He has said she died after being accidentally hit by a heavy hatch in the submarine's tower. Police have found no fractures to Wall's skull.

Madsen, the 46-year-old Danish inventor who is in pretrial detention on preliminary manslaughter charges, claims he "buried" Wall at sea after she died on his UC3 Nautillus submarine.

Police have said 15 stab wounds were found on her torso, which was found at sea off Copenhagen on Aug. 21.

Wall's cause of death hasn't yet been established yet.

The detention of Madsen, who has denied manslaughter, expires Oct. 31 when a court will decide if he will continue to remain in custody ahead of a possible trial. He is also held on preliminary charges of the indecent handling of a corpse.

A graphic from BBC News shows the events surrounding Kim Wall's disappearance and death. BBC News

Police have said the submarine only sailed in Danish waters Aug. 10-11.

Police believe the pair didn't know each other beforehand. Wall was working on a story about Madsen, who dreamed of launching a manned space mission. She was last seen alive Aug. 10 aboard the 40-ton, nearly 60 foot-long submarine as it left Copenhagen.

The following day, Madsen was rescued from the sinking submarine without Wall at his side and was arrested the same day. Police believe he deliberately scuttled the vessel.

During their investigation, police have found videos on Madsen's personal computer of women being tortured, decapitated and murdered. The videos were considered to be real, according to prosecutor Jakob Buch-Jepsen.

Investigators believe Madsen killed Wall between Aug. 10 and 11, cut up the body and attached a belt with a pipe to the torso with the purpose of making it sink, officials said, adding that her head, arms and legs had been deliberately cut off after her death.

Marks on the dismembered torso indicated that someone had tried to press air out of the body so it wouldn't float, police had said.