An autopsy and toxicology tests started on Friday on pop star Michael Jackson, but the exact cause of his death may not be determined for six to eight weeks, the Los Angeles County coroner's office said.
"The likelihood is very slim that we will have any results to release today because of the extensive tests that we're going to be performing," said Ed Winter, assistant chief coroner.
Jackson died Thursday after collapsing from a cardiac arrest at his home in Los Angeles. He was 50. Doctors at the UCLA Medical Centre tried to resuscitate him for more than an hour, his brother Jermaine said.
The autopsy was being performed by Indian-American pathologist Lakshmanan Sathyavagiswaran, who was also a star witness in the OJ Simpson case, celebrity website tmz.com reported. The website was the first to report Jackson's death Thursday.
Jackson died after being given "a heavy dose of morphine", tmz.com also reported, quoting family members.
The website said that family members were alarmed at his state and had planned to put him in a rehab facility for his addiction to morphine and prescription drugs.
Jackson's death has been shrouded in mystery. A Los Angeles police official said that given the "high-profile nature" of the death, the case had been assigned to the robbery and homicide team, but said there was no evidence of criminal wrongdoing.