Copenhagen police are moving towards charging Danish inventor Peter Madsen with murder in the death of Swedish reporter Kim Wall.

The Danish penal code uses the term manslaughter for what would be a murder charge in Canada.

Danish police are also putting an additional charge of abuse of a corpse to the court investigating whether Madsen killed Wall on board his submarine.

Police said on Wednesday, as they formally identified her headless torso, that the body had been weighted down with metal. "At the same time, the body bears the mark of having, most likely, been inflicted deliberate damage with the purpose of ensuring that gasses can pass out of the body – possibly in an attempt to avoid that a body rises from the seabed," Copenhagen police said in a press release.

On Thursday police continued a search for Wall's clothing and remaining body parts.

Members of The Danish Emergency Management Agency (DEMA) prepare to assist police at Kalvebod Faelled Thursday in a search of missing body parts of journalist Kim Wall, close to the site where her torso was found. (Scanpix Denmark/Martin Sylvest/Reuters)

Wall, who was researching a story on inventor Peter Madsen, went missing after he took her out to sea in his 17-metre submarine on Aug. 10. He denies killing her, saying she died in an accident.

The next day, Madsen was rescued after his submarine sank. Police charged Madsen the same day, and on Aug. 12, Copenhagen's City Court found there was reasonable suspicion of Madsen being guilty of involuntary manslaughter.

In its preliminary investigation, the court ordered Madsen detained until Sept. 5, pending further inquires, on the lesser charge of involuntary manslaughter.

Police will seek to extend the pre-trial custody when it is reviewed next month, again requesting he be held on the charge on manslaughter, police spokesman Jakob Buch-Jepsen said.

"We maintain the [manslaughter] charge that we've had all the time, but now we would like the court to change the basis for the custody to manslaughter from involuntary manslaughter," he said.

Under the Danish penal code, manslaughter is used to describe the deliberate killing of a person and there is no distinction between manslaughter and murder. Involuntary manslaughter is used when the killing is not intentional.

Police divers search the water off Foteviken, south of Sweden, Aug. 24 after human remains were spotted by a member of the public. ( Johan Nilsson/TT/Associated Press)

The submarine is one of three constructed by Madsen and one of the largest privately built ones in the world. It can carry eight people and weighs 40 tonnes when fully equipped.

Police still do not know the cause of Wall's death.

Madsen 'like manic,' 'short-tempered'

Susanne Johansson, a journalist with the Danish newspaper BT, interviewed Masden in 2016. In an interview with CBC Radio's As it Happens, she describes Madsen as "like manic."

She said she "could feel that he was short-tempered. Everything had to go exactly as he had planned it, and everyone had to be in line."

Peter Madsen, builder of the private submarine "UC3 Nautilus" in Dragoer harbour south of Copenhagen on Friday, August 11, following a major rescue operation after the submarine sank in the sea outside Copenhagen harbour. (Bax Lindhardt/AFP/Getty Images)

Johansson also said she "never felt any kind of danger," although she wasn't alone with Madsen.

Asked about an Agence France-Presse story that describes Madsen as eccentric, fanatical and foul-tempered, Johansson said, "That nails him down."

Danish journalist Thomas Djursing wrote a biography of Madsen in 2014. In an interview with Danish newspaper BT earlier this month, Djursing said Madsen, "is angry with God and every man," but "a man of healthy values."

Johansson said people in Scandanavia are "obsessed" with the Kim Wall case.