The headless torso of a woman found floating at sea is that of a Swedish journalist who authorities believe died aboard a Danish inventor's home-made submarine.

Divers from the Danish Defence Command preparing for a dive in Koge Bugt near Amager in Copenhagen on August 22, 2017 where a womans torso was found.
Divers from the Danish Defence Command preparing for a dive in Koge Bugt near Amager in Copenhagen on August 22, 2017 where a womans torso was found. (AFP)

Police on Wednesday identified the headless torso washed ashore in Copenhagen as that of Swedish journalist Kim Wall, who they believe was killed by a Danish inventor on board his home-made submarine.

Wall, who was researching a story on inventor Peter Madsen, went missing after he took her out to sea in his 17-metre (56-foot) submarine on August 10. 

He denies killing her.

Announcing the results of tests on the torso, discovered by a passing cyclist on Monday, police spokesman Jens Moller said it had suffered damage suggesting "an attempt to make sure air and gas inside should leave the body so that it would not rise from the seabed."

He added: "There was also some metal attached to the body, allegedly also to make sure the body would sink to the bottom."

The arms, legs and head had been sawn from the body. Analysis showed a match with Wall's DNA, which police had gathered from a toothbrush, hairbrush and with blood found in the submarine, Moller said.

Police still do not know the cause of death and divers are searching for more body parts.

Madsen, 46, was initially held on a charge of involuntary manslaughter, though a police statement in Danish on Monday referred to a 'murder charge' against him. 

Asked for clarification on Wednesday, police said the charge was manslaughter.

The macabre case has riveted Swedish and Danish media, and made headlines around the world.

Madsen's defence lawyer, Betina Hald Engmark, was not immediately available for comment, but has told Danish media he is sticking to his explanation her death was caused by an accident.

He has told a court that following the alleged accident, he "buried" Wall at sea - changing his initial statement to police that he dropped her off alive in Copenhagen.

A day after taking Wall out to sea, the inventor was rescued after his UC3 Nautilus vessel sank. 

Police found nobody else on board. 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.

"Rocket Madsen"

Madsen is already well known in Denmark as an entrepreneur and aerospace engineer, as well as for his submarines. 

He founded the association Copenhagen Suborbitals, with the goal of sending a person into space in a home-built rocket, and wrote a blog under the nickname 'Rocket Madsen'.

"He is not violent, he does not drink, does not do drugs," Thomas Djursing, who wrote a book about him, told Danish tabloid B.T. earlier this month.

"On the other hand, he quarrels with everyone and I have argued with him too. But that is how it often is with people who are deeply driven by a passion."

Wall, 30, was a freelance journalist whose work had appeared in Harper's Magazine, The Guardian, The New York Times, Foreign Policy, South China Morning Post, The Atlantic and TIME.

Source: Reuters