Prosecutors are prepared to seek an indictment of Michael Jackson's doctor on a charge of involuntary manslaughter in the pop star's death, it has emerged. A law enforcement source, who spoke on condition of anonymity because the investigation remains open, said Dr. Conrad Murray would be prosecuted on a theory of gross negligence alleging his treatment of Jackson was an extreme departure from the standard of care normally followed by physicians. The coroner has ruled Jackson's death at the age of 50 a homicide caused by acute intoxication of the powerful anaesthetic propofol with other sedatives a contributing factor. Propofol depresses breathing and the heart rate and lowers blood pressure and should be administered by an anaesthesia professional in a medical setting. The coroner found the propofol was administered to Jackson without any medical need and recommended resuscitation equipment was missing. The district attorney's office is waiting for Los Angeles police to turn over the case before presenting it to a grand jury, the law enforcement source said. A spokeswoman for the district attorney's office, however, denied that any decisions have been made.