Michael Jacksons doctor tried to hide the fact that he had given the singer a powerful anaesthetic shortly before he died, a prosecutor has said. At a preliminary hearing, the prosecutor said Dr Conrad Murray phoned paramedics only after Jackson had died. Prosecutors say Dr Murrays negligence in treating the singer for insomnia led to his death aged 50 in June 2009. Dr Murray has pleaded not guilty to involuntary manslaughter, arguing he did not cause the singers death. At the preliminary hearing, the judge is to decide whether prosecutors have enough evidence to try Dr Murray, a cardiologist. It is expected to last several days. Dr Murray faces up to four years in prison if convicted. In the courtroom in Los Angeles on Tuesday, prosecutor David Walgren said that when Dr Murray realised the singer had died, he ordered a security guard to collect medical paraphernalia and other items before having him call the authorities. BBC