LAS VEGAS (AP) — The potent anaesthetic that Michael Jackson's doctor gave him as a sleep aid came from a Las Vegas pharmacy searched Tuesday by federal drug agents and police, a law enforcement official told The Associated Press.

Authorities are investigating Jackson's June 25 death as a manslaughter and believe the anaesthetic propofol he was given at his rented Los Angeles mansion was a major factor. Propofol normally is used to render patients unconscious for medical procedures and only is supposed to be administered by anaesthesia professionals in medical settings.

As investigators build their case, a central issue is what drugs were in Jackson's system when he died and how those medications were obtained. Jackson's physician, Dr. Conrad Murray, is the focus of the investigation.

He has told investigators he administered propofol and multiple sedatives to Jackson in the hours before he died, the law enforcement official told The Associated Press.

The official spoke on condition of anonymity because the investigation is ongoing.

Los Angeles and Las Vegas police and Drug Enforcement Administration agents served a sealed search warrant Tuesday morning at Applied Pharmacy Services in Las Vegas, which the official said legally sold propofol to Murray.

Investigators discovered large amounts of the drug and other medications in Jackson's home after his death. DEA agents were able to track the anaesthetic back to the Las Vegas pharmacy.

Through a spokeswoman, Murray's attorney Edward Chernoff said he had not seen the warrant and had no immediate comment.

Murray has talked to detectives but has not spoken publicly since Jackson died. 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. It announced Monday that it has completed its work but won't release findings while the police investigation is ongoing.