A Danish inventor rescued after his home-made submarine sank has been charged with killing a female Swedish journalist who had been on board.
Anna Göransson, a spokesperson from the police in Scania, told Aftonbladet that the woman had been on board and had been reported missing by her boyfriend.
Madsen appeared on Danish television Friday to discuss the submarine's sinking and his rescue.
"I am fine, but sad because Nautilus went down", he told TV2.
The submarine sank shortly after being spotted in Køge Bay.
The ballast tank is a compartment that holds water, which is used as ballast to provide stability for a vessel. "But I guess that was pretty good because I otherwise still would have been down there".
Deputy Police Inspector Jens Moller Jensen said investigators are looking for witnesses who may have seen the woman after the time Madsen reported she disembarked.
The journalist, who has not been named, had been writing about Mr Madsen and the submarine, according to Danish and Swedish media.
Authorities say they may have to tow the submarine to port before they can get inside.
He then reported that the woman had left the vessel on Thursday evening. "They were the only two on board yesterday".
Police during the earlier search effort.
The navy initially said the sub was "found sailing" south of Copenhagen. However, navy press spokesman Anders Damgaard later said it had sunk and Peter Madsen, who built the vessel that was launched in 2008, had "been taken over to one of our ships".