Now, as some news outlets are reporting that Michael Jackson was given an injection of Demerol shortly before his death, internet gossip site TMZ is reporting that the Los Angeles Police Department is looking for the doctor, who reportedly lived with Jackson at his home.
The site says the doctor gave Jackson an injection before he died and now cannot be found. The doctor's car was towed from Jackson's driveway last night, the site said.
Authorities are seeking to clear up the mystery surrounding Michael Jackson's death, including whether drugs could have been a factor.
An autopsy is planned for Friday, though results aren't likely to be final until toxicology tests can be completed, a process that could take several days or even weeks. If a cause can be determined from the autopsy, Los Angeles County Coroner Investigator Jerry McKibben said he will announce the results.
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. "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."
Anna Nicole Smith - a Playboy model - died in 2007 due to an accidental overdose of prescription medications. Her toxicology report found a cocktail of powerful sedatives, anxiety and insomnia pills. Smith's boyfriend and two doctors were eventually charged with conspiring to give her controlled substances. The case is ongoing.
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.
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.
"When the autopsy comes, all hell's going to break loose, so thank God we're celebrating him now," Liza Minnelli told CBS' "The Early Show" by telephone.
In 2007, Jackson settled a lawsuit filed by a Beverly Hills pharmacy that claimed he owed more than $100,000 for prescription drugs over a two-year period.
After Jackson was acquitted on child molestation charges in 2005, Santa Barbara County District Attorney Tom Sneddon argued against returning some items belonging to Jackson he labeled "contraband." Sneddon said those included syringes, the drug Demerol and prescriptions for various drugs, mainly antibiotics, that were in different people's names.
More Michael Jackson coverage:
Jackson Sought London Comeback
What Happens To Jackson's Kids?
Pop Legend's Life Had Ups And Downs
Throngs Of Fans Pay Tribute To Jackson
Jackson's Health Woes Took Center Stage
From Tokyo To Rio, Fans Mourn King Of Pop
Family Attorney Blames Prescription Meds
A Collection Of CBS Videos Of Michael Jackson
The Death Of Michael Jackson, Full Coverage