A DANISH court has sentenced inventor Peter Madsen to life in prison for murdering and dismembering a Swedish journalist aboard his home-built submarine in Copenhagen harbour in August 2017.

Madsen, dressed in black, sat completely still as his sentence was handed down in the Copenhagen City Court on Wednesday.

Police detained him on August 11 last year when he emerged from his submarine without Wall, a 30-year-old Swedish journalist who was researching a story on the man who was already well known in Denmark for his submarines and his plan to send a human into space in a home-made rocket.

Later that month, police identified a torso washed ashore in Copenhagen as Wall's. Arms, legs and a head determined to be that of the victim were also later retrieved by the authorities.

“After a total assessment, the court finds that the defendant murdered Kim Wall,” Judge Anette Burkoe said.

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

The court decided that Madsen had “dismembered the body to conceal the evidence from the crime he had committed,” she said.

The prosecutors had said Wall died either by strangulation or having her throat cut. Forensics has not been able to confirm nor deny either allegation.

Madsen, 47, admitted to dismembering the body and throwing it overboard his 17-metre submarine but he denied murdering Wall.

He was also accused of "sexual assault without intercourse, of a particularly dangerous nature" in relation to the 14 interior and exterior stab wounds investigators found to Wall's genitals.

He claimed Wall died from breathing exhaust gases that had leaked into the submarine due to a technical error while he was on the deck preparing to submerge. Forensics has also not been able to back up his claim.

“The explanation is not credible and is not consistent with the following decision to dismember the body,” the judge said, noting that the jury found the murder had been planned.

A life sentence in Denmark is typically around 15 years without parole.

Wall's closest relatives were not present in court on Wednesday. Her mother had previously said: “She gave a voice to the weak, the vulnerable and marginalised people. That voice would have been needed for a long, long time. Now it won't be so.”

Madsen will appeal against the sentence, his defence lawyer told the court. The defendant had sought a minimum sentence of six months in prison for dismembering the corpse.