Media tycoon Robert Maxwell was under investigation for alleged war crimes at the time of his death, it has emerged. Detectives were considering Maxwell's admission that while serving as a British Army captain in World War II he shot dead a German civilian. A Metropolitan Police file was released to the paper under the Freedom of Information Act. It shows that detectives at the Metropolitan Police were preparing a case for the Crown Prosecution Service. The incident is said to have taken place in April 1945, when his platoon was trying to capture a German town. Maxwell said he shot dead the town's mayor after a tank opened fire on them. Police began an investigation into the killing when the War Crimes Act came into effect in 1991, following a complaint from a member of the public. The inquiry was apparently still under way when Maxwell's body was found at sea. The police file says the case was closed the following year, because it could be "progressed no further".