Was Michael Jackson' killed? Did his comeback try kill him? Death linked injection of painkiller Demerol

Speculation was rampant Friday that pop icon Michael Jackson's mysterious death might have been caused by a lethal injection of pain-killing drugs.

An autopsy has been scheduled for Friday afternoon.

Los Angeles County Coroner Investigator Jerry McKibben said it could take weeks to determine to complete toxicology tests that would indicate whether Jackson had alcohol or drugs in his system.

McKibben added that if the cause of death can be determined by the autopsy alone, he would announce the results. The British Sun tabloid reported that Jackson aides told emergency room doctors at UCLA Medical Center, where he died, that the star had collapsed after an injection of Demerol - a powerful pain killing drug similar to morphine and known to carry a risk of cardiac arrest.

"Shortly after taking the Demerol he started to experience slow shallow breathing," the newspaper quoted one source as saying. "His breathing gradually got slower and slower until it stopped."

Hospital officials haven't confirmed that account. Jackson family lawyer Brian Oxman told CNN Jackson's sudden death "is not something which has been unexpected....I can tell you for sure that this is something I warned about."

Oxman said Jackson had been struggling to cope with pain from several performance injuries, including a damaged vertebra and a broken leg, which had been interrupting scheduled rehearsal for his upcoming London tour dates.

"This family has been trying for months and months to take care of Michael Jackson," Oxman said.

"The people who have surrounded him have been enabling him. If you think that the case of Anna Nicole Smith was an abuse, it is nothing compared to what we have seen taking place in Michael Jackson's life."

The singer reportedly got hooked on Demerol and morphine during his 2003 trial for child sex abuse.

Los Angeles homicide detectives searched the rented mansion in the posh Holmby Hills section of the city - once the home of film star Sean Connery - where the singer had been living.

Police officials said the search was routine in high-profile cases. Jackson died at UCLA Medical Center Thursday afternoon after being stricken at the Holmby Hills mansion Paramedics tried to resuscitate him at his home for nearly 45 minutes, then rushed him to the hospital, where doctors continued to work on him.

"It is believed he suffered cardiac arrest in his home. However, the cause of his death is unknown until results of the autopsy are known," his brother Jermaine said.

On Wednesday, Jackson attended a rehearsal at LA's Staples Center to prepare for a series of 50 concerts scheduled to start next month at London's O2 dome and continue into next year.

He had been spending untold hours working with a team of dancers for a performance he and his fans hoped would restore his tarnished legacy. Jackson's close friend, the psychic entertainer Uri Geller, suggested that Jackson's anxiety over planned comeback concerts may have killed him.

"I guess the stress, the anticipation and the passion he was emitting from his heart, wanting to do this comeback so badly, maybe that got to him," Geller said.

"That is all I can think, that maybe the stress killed him."

Despite rumors of Jackson's ill-health, the promoters of his London shows, AEG Live, said in March that he had been given a 4 1/2 hour physical exam by independent doctors in March and passed.

Four of Jackson's 'This Is It' concert dates were pushed back last month but AEG president Randy Phillips insisted the changes had "absolutely nothing to do with [Jackson's] health."

The death of the eccentric but undisputed King of Pop brought a tragic end to a stunning decades long career, which never recaptured its luster after falling from its peak in the 1980s, when his soulful voice and feverish, crotch-grabbing dancing dominated the charts and dazzled the world.

His 1982 album "Thriller" - which included the blockbuster hits "Beat It," "Billie Jean" and "Thriller" - is the best-selling album of all time, with an estimated 50 million copies sold worldwide.

The charismatic entertainer's dramatic death left the music world - and his adoring public - in deep mourning and rekindled sadness over his increasingly erratic career and the child sex-abuse allegations that left him forever labeled "Wacko Jacko."

Jackson, eventually accused of abusing three boys, was never convicted of any crimes.

"I am so very sad and confused with every emotion possible," said a stricken Lisa Marie Presley, daughter of Elvis Presley who was married to Jackson in the mid-1990s.

"I am heartbroken for his children who I know were everything to him and for his family. This is such a massive loss on so many levels, words fail me." Jackson's sister, Janet, was "grief-stricken and devastated at the sudden loss of her brother" and flying back to California to be with her family, according to a statement released through her manager.

Jackson's death prompted broadcasters across the world to interrupt morning programs, while fans remembered a "tortured genius" whose squeals and sliding moves captivated a generation and sparked global trends in music, dance and fashion.

Even world leaders weighed in.

Venezuelan President Hugo Chavez called it "lamentable news," though he criticized the media for giving it so much attention. Former South Korean President Kim Dae-jung, who had met Jackson, said: "We lost a hero of the world."

"I am absolutely devastated at this tragic and unexpected news," said legendary music producer Quincy Jones, who collaborated with Jackson on three of his best-selling albums, "Off the Wall," "Thriller" and "Bad."

"For Michael to be taken away from us so suddenly at this young age, I just don't have the words," Jones added.