Danish DIY sub 'deliberately sank' after journalist vanished: police

Police probing the mysterious disappearance of a Swedish journalist last seen boarding a homemade submarine said Monday its Danish inventor, accused of manslaughter, deliberately sank the craft.

Kim Wall, 30, vanished after having boarded the 60-foot (18-metre) Nautilus sub on Thursday evening, apparently as part of her work on a feature story about its owner, inventor and entrepreneur Peter Madsen.

"The investigations confirm that the sinking of the submarine was allegedly a consequence of a deliberate act," Copenhagen police said in a statement.

Early Friday, Danish authorities announced they were looking for the Nautilus in waters off Copenhagen.

The vessel was located in a bay in Koge, some 50 kilometres (30 miles) south of the Danish capital. Just after being found, Madsen was rescued and the submarine suddenly sank.

Madsen said in media interviews after his rescue that the sub encountered a problem with the ballast tank.

The Nautilus was refloated and towed to the Copenhagen port on Saturday, then emptied of water overnight. On Sunday police entered the sub and found it empty.

Madsen, who describes himself on his website as an "inventrepeneur", claims he dropped off Wall on Refshaleoen island on Thursday after she had completed her interview.

The 46-year-old is accused of negligent manslaughter and was on Saturday remanded in custody for 24 days. He denies the charges and his lawyer says her client is "hurt" by the accusation.

Wall is a freelance journalist based in China and the US. Her articles have appeared in the New York Times and the Guardian, among others.

"We're still hoping that we'll find Kim Wall alive, but we are preparing ourselves for the fact that she may not be," Copenhagen homicide police chief Jens Moller said Sunday.

Swedish and Danish authorities are cooperating on the search for the missing reporter.

Madsen, who was described in a 2014 book as "Denmark's Do-It-Yourself Astronaut", had wanted to launch himself into the space race before building the crowd-funded Nautilus, the biggest privately-made one ever when he built it in 2008.