Michael Jackson's death has been ruled a homicide caused by a mix of drugs meant to treat insomnia, a law enforcement official said. Jackson's personal doctor told investigators he was trying to wean the "King of Pop" off propofol, the powerful anesthetic that killed him.

Conrad Murray AP PHOTO

Forensic tests found propofol combined with at least two sedatives to kill Jackson, according to the official, who spoke Aug. 24 on condition of anonymity because the findings have not been publicly released. Based on those tests, the Los Angeles County coroner has ruled the death a homicide, the official said.

The homicide ruling does not necessarily mean a crime was committed. But it makes it more likely criminal charges will be filed against Dr. Conrad Murray, the Las Vegas, Nevada, cardiologist who was caring for the pop star when he died June 25 in a rented Los Angeles, California, mansion.

A search warrant affidavit unsealed in Houston, Texas, where Los Angeles police took materials from one of Murray's clinics in July as part of their manslaughter investigation, includes a detailed account of what detectives say Murray told them. Manslaughter is homicide without malice or premeditation.