According to three sources who spoke with the newspaper, by the time Murray returned, the singer was not breathing.
Murray has emerged as the central figure in the ongoing probe into Jackson's June 25 death. On Tuesday, local police and federal drug agents searched a Las Vegas pharmacy and uncovered evidence showing Murray legally purchased propofol from the business, according to a law enforcement official who requested anonymity because the investigation is ongoing.
Murray told investigators he administered the anesthetic and multiple sedatives to Jackson in his rented Beverly Hills mansion in the hours before he died, the official told The Associated Press. Propofol is normally used to render patients unconscious for medical procedures and only is supposed to be administered by anesthesia professionals in medical settings.
According to the LA Times report, a law enforcement source has said Jackson's use of the anesthetic goes back a decade. Murray, who was hired by the singer in May, said he felt that based on his history with the drug, it was acceptable to leave him alone to make the calls that morning.
While it is extremely strong, propofol is not a controlled substance so investigators are looking for evidence to show Murray was negligent in administering it. A central issue for detectives on the case is what drugs were in Jackson's system when he died and how those medications were obtained.
Murray has talked to detectives but has not spoken publicly since Jackson died. His attorney Edward Chernoff has said Murray gave Jackson nothing that "should have" killed him and specifically said the physician did not give Jackson the narcotic painkillers Demerol or OxyContin.
The cause of death for Jackson and details about what was in his system will be revealed in the final autopsy report prepared by the Los Angeles County coroner's office.
The office announced Monday that it has completed its work but won't release findings while the police investigation is ongoing.