LOS ANGELES — Authorities are seeking to clear up the mystery surrounding Michael Jackson's death, including whether prescription drugs could have been a factor.

An autopsy was to begin Friday, though results weren't likely to be final until toxicology tests could be completed, a process that could take weeks. However, if a cause can be determined by the autopsy, they will announce the results, said Los Angeles County Coroner Investigator Jerry McKibben.

In a press conference Friday, Lt. Ed Winter, assistant chief coroner, said the likelihood was slim that the coroner's office would have anything to release today and said results could take 6-8 weeks.

"We're conducting it as we do any other exam," said Winter.

Police said they were investigating, standard procedure in high-profile cases.

Brian Oxman, a former attorney of Jackson's and a family friend, said he was concerned about Jackson's use of painkillers and he warned the singer's family about possible abuse.

"I said one day, we're going to have this experience. And when Anna Nicole Smith passed away, I said we cannot have this kind of thing with Michael Jackson," Oxman said Friday on NBC's "Today" show. "The result was, I warned everyone, and lo and behold, here we are. I don't know what caused his death. But I feared this day, and here we are."

The 50-year-old musical superstar died Thursday, just as he was preparing for a series of 50 concerts starting July 13 at London's 02 arena.

He died at UCLA Medical Center after being stricken at his rented home in the posh Los Angeles neighborhood of Holmby Hills. Paramedics tried to resuscitate him for nearly three-quarters of an hour, then rushed him to the hospital, where doctors continued to work on him.

His brother Jermaine said it was believed that Jackson suffered cardiac arrest at his home. Cardiac arrest is an abnormal heart rhythm that stops the heart from pumping blood to the body. It can occur after a heart attack or be caused by other heart problems.

A handful of bleary-eyed fans camped out throughout the night with media outside the Jackson family house in the San Fernando Valley and near his star on the Hollywood Walk of Fame. People heading to work in New York on Friday were stopping at a makeshift memorial outside Harlem's Apollo Theater, where Jackson performed as a child.

Oxman, who said he was speaking on behalf of no one but himself, and other friends made the rounds among the news outlets Friday, adding to the intrigue of Jackson's early demise. Oxman claims Jackson had prescription drugs at his disposal to help with pain suffered when he broke his leg after he fell off a stage and for broken vertebrae in his back.