Jurors watched videos found on a murder suspect's hard drive, which showed women being decapitated and impaled.

Danish inventor Peter Madsen (47) is accused of torturing and killing Swedish journalist Kim Wall during a private submarine trip.

The inventor denies killing Ms Wall, telling prosecutors: "I've never been violent to any human being - and no dead human being either".

Madsen says the 30-year-old freelance journalist died when the air pressure suddenly dropped and toxic fumes filled his homemade submarine, while he was up on deck.

Kim Wall | File photo

He has admitted dismembering her body and throwing it overboard, but denies the charge of premeditated murder.

The prosecution has meanwhile painted a picture of Madsen as a sexual sadist, who was obsessed with beheadings and murdered Ms Wall as part of a sexual fantasy.

The court was shown violent videos found on Madsen's hard drive.

This article contains graphic details some readers may find distressing

One animated video showed a woman dancing while taking her clothes off.

She then sits down naked before a man moves behind her and slits her throat several times. He decapitates her and holds her head in one hand.

When the prosecutor asked Madsen why he watched the movie, he replied: "Why, have you seen Seven?", referencing a violent thriller which revolves around grizzly murders.

A video called 'Beheading girl' which showed a real woman having her throat slit was also shown to court.

Prosecutors say Madsen watched the 54-second film on the night before Ms Wall's death.

Madsen had searched online the words "beheading" and "girl".

The inventor says other people had access to the hard drive and he rejects any link between watching such videos and actually beheading someone.

Madsen, who at some points during the hearing referred to himself in the third person, reiterated his argument that he searched for such material for "emotional reasons, not erotic reasons."

A motive has not been established for the alleged murder and an autopsy has been unable to determine Ms Wall's cause of death.

Prosecutors say evidence shows Madsen bound Ms Wall around the head, arms and legs before beating her and stabbing her repeatedly in her genital area.

They say the journalist was stripped and then dismembered with a saw, before her body parts were put in bags, weighed down and dumped in Koge Bay, off Copenhagen.

Asked about cutting up Ms Wall's body, Madsen refused to go into detail, saying: "It's something so horrible that I do not want to go into detail. I will just say, that it was horrible."

Peter Madsen's submarine 'Nautilus' sits on dry land in Copenhagen, Denmark | Image: Theresa M?nch/DPA/PA Images

The accused appeared less relaxed in court than during his previous appearance, at some points sitting on his hands and leaning forward, with his feet crossed under the table.

He was dressed simply, in a black t-shirt and blue jeans.

Madsen told the court the 14 stab wounds to Ms Wall's genital area were not sexual in nature, saying he was not sexually attracted to her.

"I considered where gases build up inside dead people when they decompose. They do so in different places. Therefore I tried to puncture that region," he said.

"There is nothing sexual in the stabs hitting her vagina. I know you would like to think so, but to me there is nothing sexual to that," he told the prosecutor.

The accused also told the Copenhagen court he occasionally filmed his sexual encounters with women with an action camera mounted on his forehead.

Thirty-seven experts and witnesses are expected to testify over the coming days to evaluate the credibility of Madsen's accident scenario, and help understand the psychology of the self-taught engineer, described by the prosecution as "a perverted polymorph, and highly sexually deviant".

Madsen has admitted lying to investigators and changing his account of what actually happened to Ms Wall several times.

The prosecution has said it will seek a life sentence, which in Denmark averages around 16 years, or safe custody, a legal alternative which would keep him behind bars indefinitely as long as he is deemed dangerous.

The trial ends on April 25th, with a verdict expected the same day.