Police in Copenhagen say they are charging submarine enthusiast and rocket builder Peter Madsen in connection with the death of a missing Swedish journalist.
The Dane is the skipper and designer of the UC3 Nautilus, a privately-owned submarine which sank off the Danish coast on Friday.
Some reports describe Mr Madsen as a "hobby engineer", and it is not clear what his background and training is.
While building his own crowd-funded submarine might seem challenging enough, after completing the Nautilus - which he claims is the world's biggest privately-built submarine - in 2008, he moved on to a more lofty ambition - space exploration.
He now runs an organisation called Rocket-Madsens Space Laboratory, which is funded by donations, and aims to launch a rocket from a floating platform in the Baltic, near the island Bornholm.
A crowd-funding page was set up for the Nautilus prior to 2014 to attempt to raise $50,000 (?39,000) to cover refurbishment costs - just $6,170 was raised. At that time the Nautilus had logged more than 1,000 dives and had a team of 10 volunteers working on her refurbishment.
In 2015, after a dispute with the group of volunteers maintaining it, ownership of the Nautilus was transferred to Mr Madsen, says a statement on the website (in Danish).
"You may think that a curse is lying on Nautilus. That curse is me," he had messaged members of the board, according to the statement. "There will not be peace of Nautilus for as long as I exist."
The craft finally re-launched earlier this year. It has a diesel and an electric motor and is 17.8m in length.
According to the crowd-funding page, Danish law prohibited the Nautilus's operators from taking on passengers, but the team offered tours of the craft while docked "to give you the full experience of being aboard a real submarine".
Both Rocket-Madsens Space Laboratory and Copenhagen Suborbitals - which Mr Madsen co-founded but has since left - are trying to become the first non-government, all-volunteer organisation to launch a human being into space.
The two organisations are in conflict over their launch area, and seem to communicate via blog warfare.
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