Swedish journalist Kim Wall died by accident after being hit by a hatch cover onboard a submarine, the Danish owner of the vessel has told a court.
Peter Madsen said he had been holding the heavy hatch - but then lost his foothold and the hatch shut.
Mr Madsen, 46, said he had then tried to bury Ms Wall, 30, at sea and intended to commit suicide.
He has been charged with killing Ms Wall, whose headless torso was found on 23 August in waters off Denmark.
She was last seen alive on 10 August as she departed with Mr Madsen on his home-made submarine to interview the inventor.
Prosecutors have accused Mr Madsen of murdering Ms Wall and mutilating her body. He denies this.
Testifying in Copenhagen's court on Tuesday, Mr Madsen said Ms Wall was bleeding intensely after being hit the 70kg hatch.
"There was a pool of blood where she had landed."
"In the shock I was in, it was the right thing to do," he said, answering why he threw the journalist overboard.
Danish police believe Mr Madsen deliberately sank the 40-tonne submarine hours after the search for Ms Wall began on 11 August.
Her partner had reported that she had not returned from the trip.
Mr Madsen was rescued from waters between Denmark and Sweden.
Local authorities are continuing their search for the rest of Ms Wall's remains, hoping that this will provide clues about the cause of her death.