COPENHAGEN (AFP) - Videos of women being decapitated alive have been found on the hard drive of a maverick Danish inventor accused of murdering a Swedish journalist aboard his home-made submarine, the prosecutor said on Tuesday (Oct 3).

Accused of Kim Wall's death and desecrating her body by throwing it overboard, self-taught engineer Peter Madsen appeared in court where his custody was extended until Oct 31.

In a case that has gripped world audiences, Wall, 30, vanished after interviewing Madsen aboard his submarine on Aug 10.

Her headless torso was found floating in waters off Copenhagen on Aug 21.

Madsen, 46 and married, has maintained that she died on board when a 70kg hatch door fell on her head, and in a panic he threw her overboard. He insisted her body was intact at the time.

Prosecutors believe however that he dismembered her before throwing her into the sea.

Prosecutor Jakob Buch-Jepsen told the court on Tuesday that a hard disk found in Madsen's workshop contained fetish films in which real women were tortured, decapitated and burned.

"This hard drive doesn't belong to me," Madsen insisted, saying numerous people had access to his workshop.

"We had, among others, an intern living there," he said.

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Prosecutors believe Madsen killed Wall as part of a sexual fantasy, then dismembered and mutilated her body.

The final autopsy on the torso was not able to establish the cause of death. However, it did show multiple mutilation wounds to Wall's genitals.

Police continue to search for the rest of her remains.

Wall worked as a freelance journalist based in New York and China, and her articles were published in The Guardian, The New York Times and others.