Michael Jackson’s family want an independent autopsy to determine the cause of his death, the politician the Rev Jesse Jackson claimed yesterday after seeing them.

Jesse Jackson said the family wanted answers to questions surrounding the singer’s death, including the role of the personal cardiologist, Dr Conrad Robert Murray, who was with him when he died.

The Los Angeles County coroner’s office performed an autopsy on the singer’s body on Friday, but failed to determine what killed the 50-year-old entertainer, pending toxicology tests that are expected to take four to six weeks.

Coroner’s officials said they released Jackson’s body to his family late on Friday night. According to the website TMZ, which first broke the story of his death, the private autopsy had begun last night.

Police are hoping to interview Murray, whose car was impounded as evidence in an expanding investigation into Michael Jackson’s prescription drug habits, said to range from anti-depressants to Vistaril, which amplifies the effects of other drugs.

Murray’s lawyer, Bill Stradley, said the 51-year-old Houston cardiologist was co-operating and was expected to start being interviewed by police late last night. “The impression that he has been hiding from authorities, that’s not correct,” said Stradley. “Contrary to what has been out there, Dr Murray has been co-operating with authorities from the outset.”

A three-hour autopsy carried out by public officials on Friday revealed traces of the powerful painkillers OxyContin and Demerol, which the family believe was injected into the singer less than an hour before he collapsed and died on Thursday.

Sources at the mortuary said they found the singer’s body to be in a better condition than expected for a man with a history of health problems.

Jesse Jackson, a family friend who spent Friday with the star’s stricken parents, Joe and Katherine, said: “The family have questions for the doctor. What did he inject him with and did he inject him once or twice? Did he panic and flee?

“His absence at this time has given them substantial reason to be suspicious of him, because he is not around to answer their questions. I think they should and will proceed with a second autopsy as soon as possible.”

Doctors who listened to a taped telephone call from Murray’s aide to ambulance dispatchers as Jackson lay dying were puzzled that Murray was trying manual cardiopulmonary resuscitation (CPR) techniques on his patient on a bed.

Daniel Simon, an Ohio cardiologist, said that every doctor knew that CPR had to be carried out on a hard surface, not a bed. He also pointed out that many cardiologists on call travel with a more effective battery-operated defibrillator, which are sold in high street shops for as little as $900 (£550).

Murray is believed to have struck up a friendship with the singer when he treated him in Las Vegas last year.

Officials from the concert promoter AEG said Jackson insisted the doctor lived with him and it was preparing to pay a significant amount of money to Murray to remain at the singer’s side during the planned 50-date engagement at London’s O2 Arena. Two weeks ago Murray “suspended” his practice in Las Vegas where a court had recently ordered him to pay $400,000 in a civil case, with two other cases pending.

The night before he died Jackson had danced through a four-hour rehearsal at the Staples Centre, a downtown Los Angeles sports arena with a similar capacity to the O2.

The presence of officials from the concert promoter, who were there to see what Jackson planned to bring to the London venue next month, had pressured or inspired him to execute an “extraordinary” set of 12 songs, a performance that left him “dripping and in pain”. The family believe he would have been in extreme discomfort the next morning.

According to police Murray gave Jackson a Demerol injection at about 11.30am and was alone with him when less than an hour later he went into cardiac arrest.

Five detectives from the Los Angeles robbery homicide division will this weekend continue interviewing the 15- strong entourage that lived with Jackson and his three children in a rented chateau-style home in west Los Angeles. Investigators want to know how often Jackson used prescription drugs in his last few weeks.

Brian Oxman, a former Jackson lawyer who has been acting as the family’s spokesman, said he had long been concerned that Jackson, who had quit painkiller addictions before, had again succumbed to mood-altering drugs supplied by a circle of shady “enablers”.

“This is something that I warned his family about,” said Oxman, “but they could not always be there. They have been trying to look after him for months, but enablers got in the way. I do not know what he has been taking, but I suspect he had been taking a lot.”

Deepak Chopra, an Indian-American doctor and friend of Jackson for 20 years, said that after his 2005 trial for child molestation Jackson had asked him for an OxyContin prescription: “He first denied he had a problem and then admitted he was getting narcotics from several doctors.”

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