The picture shows submarine UC3 Nautilius in early sea trials of her then-newly fitted propulsion and rudder system, operated by submarine builder and architect Peter Madsen (August 2008). (Web Picture)

COPENHAGEN, Oct. 30 (Xinhua) -- Danish submarine owner Peter Madsen changed his explanation of what had caused the death of Swedish journalist Kim Wall, but insisted that he had not killed her, local media reported Monday.

Madsen said in a new interview with the police that Wall died of carbon monoxide poisoning while on the deck of the submarine, according to Danish news agency Ritzau.

Earlier, he said that Wall died when she was hit by a heavy hatch in her head and he subsequently threw the body intact into the ocean.

In the new interview, he also acknowledged that he had dismembered the Swedish journalist, who was last seen on Aug. 10 when she went inside the 18-meter submarine with Madsen.

"This explanation naturally causes the police to collect various additional statements from both the forensics and the submarine experts," deputy police inspector Jens Moeller Jensen was quoted as saying.

Madsen has volunteered to extend his custody until Nov. 15, Ritzau reported, citing his lawyer.