On 5 October 1999 he was put on trial and found guilty of 15 murders. On 31 January 2000, he was sentenced to life imprisonment for each murder. On 10 February 2000, exactly 10 days after his conviction, he was struck off from the General Medical Council Register. An investigation identified another 235 suspicious deaths. His usual way of killing was using morphine. Most of the patients he killed were old women.