madsen was arrested upon being rescued from køge bay after "uc3 nautilus" foundered on 11 august 2017, and was charged with negligent manslaughter. police suspected that he had scuttled the submarine. he initially stated that he had dropped wall off on land, but then admitted to dumping her body at sea after she died in what he claimed was an accident on board the submarine. he testified in a court hearing on 5 september that wall died after being struck on the head by the submarine's hatch cover. the prosecution said that police had found videos on madsen's computer showing women being murdered, and that witnesses said that they had seen madsen watching videos of decapitation and practising asphyxiation sex. a post-mortem examination performed on wall's head after it was found a month later found no signs of blunt trauma to the head and did not determine the cause of death. madsen subsequently changed his story, admitting to dismembering wall's body but continuing to deny intentionally killing her, saying that she may have died after poisonous exhaust gases entered the submarine while he was on deck. the post-mortem performed on wall's torso showed no signs of exhaust gases in her lungs.