The Los Angeles County coroner’s finding that the death of Michael Jackson was a homicide could mean criminal charges for his doctor, who told investigators that he administered a mix of powerful drugs to treat the pop star’s insomnia hours before his death.

The homicide ruling was based on forensic tests that found the anaesthetic propofol combined with at least two sedatives to kill Jackson, a law enforcement official told The Associated Press on Monday, speaking on condition of anonymity because the findings have not been publicly released.

While the finding does not necessarily mean a crime was committed, it means more likely that criminal charges will be filed against Dr. Conrad Murray, the Las Vegas cardiologist who was caring for Jackson when he died June 25 in a rented Los Angeles mansion.

Through his lawyer, Dr. Murray has said he administered nothing that “should have” killed Jackson.

He told investigators that at the time of the King of Pop’s death, he had been trying to wean Jackson off propofol. The doctor said he had been treating Jackson for insomnia for about six weeks with 50 milligrams of the drug every night via an intravenous drip, said a search warrant affidavit.

Dr. Murray said he feared Jackson was becoming addicted to the anaesthetic, which is supposed to be used only in hospitals and other advanced medical settings.

The affidavit unsealed in Houston, where Los Angeles police took materials from one of Dr. Murray’s clinics last month as part of their manslaughter investigation, includes a detailed account of what detectives say Dr. Murray told them. Manslaughter is homicide without malice or premeditation.