Prosecutors say Danish inventor Peter Madsen tied up and tortured Swedish reporter Kim Wall before he either cut her throat or strangled her during a trip on his private submarine in August.

Madsen, 47, is charged with murder, dismemberment and indecent handling of a corpse for the way he disposed of Wall's body. The charges were made public Jan 16. but not in detail.

A charge sheet obtained Tuesday by the AP said Wall's murder was premeditated because Madsen brought along tools he normally didn't take when sailing.

He has denied murder, and claims Wall died accidentally inside the submarine while he was on deck during the excursion. He has admitted throwing her body parts into the sea.

His trial starts March 8.