Danish self-taught engineer Peter Madsen goes on trial this Thursday. He is charged with murdering and mutilating Swedish journalist Kim Wall last year aboard his homemade submarine. The Copenhagen Court House will call 37 witnesses during the 12-day trial, which could help to clarify seemingly contradictory statements by the 47-year-old accused. The engineer has admitted to cutting up Wall’s body but denies murdering her aboard the vessel, where she was last seen on August 10, AFP reports. Madsen has changed his story several times, initially saying he had dropped Wall off at a Copenhagen harbor. Then, he said she died in an accident onboard the vessel. Prosecutors believe Madsen planned to murder Wall. A well-known figure in Denmark, he was dubbed ‘Rocket Madsen’ due to his ambitions relating to amateur space travel and rocket launches.