TALLINN, Estonia -- A Danish inventor has admitted dismembering a Swedish journalist who disappeared from his home-made submarine in August and has changed his story about how she died, but still denies killing her, police investigating the bizarre case said Monday.

According to Copenhagen police, Peter Madsen now says Kim Wall died as result of carbon monoxide poisoning inside the submarine while he was on deck. Previously he had said she died after being accidentally hit by a heavy hatch in the submarine's tower.

"This explanation (by Madsen) naturally will lead the police into gathering additional statements from the coroner and the armed forces' submarine experts," said Copenhagen police investigator Jens Moller Jensen.

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Police say Madsen acknowledged he dismembered her body and threw it into Koge Bay southwest of Copenhagen.

"Kim Wall had suffered 14 stabs in and around the genitals and it is due to these stabs that we have said that there must have been a sexual motive," Jensen told reporters, according to Reuters news agency.

Wall's torso was found on a southern Copenhagen coast in late August, and her head, legs and clothes were found at sea this month.

No fractures to Wall's skull were found that would have supported the claim that she was killed by the hatch.

Wall was working on a story about Madsen and was last seen aboard his homemade submarine Nautilus as it left Copenhagen in August.

The next day, Madsen was rescued from the sinking submarine without Wall. Police believe he deliberately sank the vessel.

Madsen's pre-trial detention is set to expire Tuesday but police said no new hearing will be held as the 46-year-old has voluntarily agreed to remain in detention.