LOS ANGELES - The body of Michael Jackson has been released to his family for burial, a Los Angeles County coroner's spokesman said on Saturday, after an autopsy failed to immediately determine what killed the troubled pop star.

Members of Jackson's family were said to be gathering at his parents home in suburban Los Angeles to plan a funeral for the King of Pop, whose sudden death on Thursday dominated worldwide headlines and touched off two days of tributes from fans.

No funeral plans have been disclosed to the public.

Coroner's officials have said that with no outward signs of trauma to Jackson's body or evidence of foul play, they would have to wait for the results of toxicology tests and other studies to establish a cause of death.

Speculation has centered on Jackson's use of prescription drugs and reports that he was injected with the narcotic painkiller Demerol shortly before collapsing at his rented mansion in a Holmby Hills neighborhood of Los Angeles.

The 50-year-old entertainer was in full cardiac arrest when paramedics arrived, with his personal physician, identified as Dr. Conrad Murray, trying desperately to revive him.

Police towed Murray's silver Mercedes from the driveway of the home where Jackson died, saying they wanted to search it for evidence and medication, and have sought to arrange further interviews with the Houston-based cardiologist.

The Los Angeles Times reported that Murray had agreed to meet with detectives with his attorney present, although he has not been accused of any wrongdoing.

Jackson's body was held under tight security at the Los Angeles County Coroner's Office, a spokesman said, and transferred to an area mortuary shortly after 9 p.m. local time on Friday night (12:00 a.m. EDT on Saturday).

Few details were released about the autopsy's findings, but Fox News reported on its website that investigators found his body to be healthier and stronger than they had expected with some scarring on the face.

Celebrity website TMZ.com, citing an interview with an unidentified close member of the Jackson family, has reported that the entertainer was injected with Demerol about half an hour before he went into cardiac arrest.

TMZ, citing family members, said Jackson received a daily shot of Demerol, a narcotic painkiller, and that the family believed his death was caused by an overdose of the drug.

A senior law enforcement official told ABC News that Jackson was heavily addicted to the painkiller Oxycontin and was injected daily with that medication, along with Demerol.

Facing a battered reputation and a mountain of debt that The Wall Street Journal reported ran to $500 million, Jackson spent the last two months of his life rehearsing for a series of London concerts that were seen as a make-or-break comeback for the man who dominated the pop charts in the 1980s.

(Editing by Sandra Maler)