Submarine inventor Peter Madsen gets life sentence life for torturing and murdering Swedish reporter Kim Wall

Danish submarine inventor Peter Madsen has been sentenced to life in prison for torturing and murdering Swedish reporter Kim Wall.

The 47-year-old denied murder and said Ms Wall died accidentally inside the submarine after she fell and hit her head.

The cause of death has never been established.

However, he did confess to cutting up the 30-year-old's body and throwing the parts into the sea.

Yet Judge Anette Burkoe at the Copenhagen City Court said she and the two jurors agreed Ms Wall's death was a "cynical murder", saying Madsen did not given "a trustworthy" explanation.

Madsen has said he will appeal the murder conviction and life sentence.

The court ruled that Madsen should stay in jail until his appeal hearing out of fear Madsen can influence witnesses.

In Denmark, a life sentence is 16 years long, but Madsen could spend the rest of his life behind bars after psychiatrists recommended that he be detained indefinitely.

They said they believed that Madsen was not insane, but is a danger to the public, and should be released only if and when it is deemed "safe" to do so.

During the trial, which began on March 8, prosecutor Jakob Buch-Jepsen claimed Ms Wall's murder was sexually motivated and premeditated because Madsen brought along tools he normally did not take when sailing, including a saw and sharpened screwdrivers.

Yet Madsen's defence lawyer argued for his acquittal on the charge of murder, saying he should only be sentenced on the lesser charge of cutting Ms Wall's body into pieces.

Madsen is a minor celebrity in Denmark known for his self-funded, somewhat madcap engineering projects.

He constructed the 33-tonne Nautilus - the submarine on which Ms Wall disappeared - and has also built rockets, hoping to become the first Dane to send himself into space in a homemade rocket.

Ms Wall - who was published in the Guardian and Time Magazine - had wanted to write a story about Madsen and was invited to take a trip on the submarine on August 10.

She told her boyfriend she would only be gone for a few hours, but Ms Wall never returned from that voyage.

Although the submarine was initially spotted afloat, it later sank south of Copenhagen and Madsen was picked up unharmed.

He told police he had let Ms Wall off on Refshale island several hours into the trip, but later changed his story.

Investigators found dried blood inside the submarine, and divers eventually uncovered Ms Wall's body parts in plastic bags weighed down on the Baltic Sea bed.

Her torso was found by a cyclist along the shoreline. It contained 11 stab wounds.