COPENHAGEN, Denmark (AP) — A judge is set to decide if the owner of an amateur-built submarine should be held in custody during an investigation into whether he is responsible for the disappearance of a Swedish woman who had been onboard his submarine that sank off Denmark’s east coast.

Peter Madsen was arrested Friday on preliminary manslaughter charges after his 40-ton, nearly 18-meter-long (60-foot-long) UC3 Nautilus sank. He has denied responsibility for the 30-year-old woman’s fate, saying she disembarked earlier.

The woman’s boyfriend alerted authorities that the sub had not returned, prompting a major maritime search. The Navy said it was spotted sailing but then sank.

Madsen told authorities he dropped the woman off on an island in Copenhagen’s harbor a few hours into their Thursday night trip.

The hearing starts at 1200 GMT.