Michael Jackson suffered from crippling insomnia and pleaded for a powerful sedative in the days leading up to his death, according to a nutritionist who was working for the pop star.

Cherilyn Lee said that she repeatedly rejected his demands for the drug, Diprivan, which is given intravenously. The singer told her that he had been given it in the past by an unnamed doctor.

Several months ago, Jackson had begun badgering Ms Lee about Diprivan, also known as Propofol, she told the Associated Press. It is an anaesthetic drug widely used in operating rooms to induce unconsciousness, generally given through an IV needle in the hand.

The powerful drug has a very narrow therapeutic window, meaning it does not take doses much larger than the medically recommended amount to stop a person's breathing, leading to cardiac arrest.

The LA coroner's office performed an autopsy on the 50-year-old singer's body on Friday but deferred a decision on the cause of death, ordering toxicology tests. A second, private autopsy has been requested by the family, over concern about his final hours. Persistent reports claim that Jackson was addicted to painkillers and other prescription medicines.

The Jackson family has questioned the role of the singer’s physician, Conrad Murray, who was with him when he collapsed. It took as long as 30 minutes for paramedics to be called after Dr Murray found Jackson with a faint pulse and performed CPR.

Lawyers for Dr Murray, who had been treating Jackson for three years and who had recently moved into the rented mansion, have issued a categorical denial that the doctor had administered an injection of Demerol, a narcotic painkiller, to Jackson before his death.

Ms Lee, 56, a registered nurse whose specialty includes nutritional counseling, said she received a frantic phone call from Jackson's staff on June 21 that the star needed her. She was in Florida at the time and told the staff member to take him to hospital.

"At that point, I knew that somebody had given him something that hit the central nervous system," she said, adding, "He was in trouble Sunday and he was crying out."

Jackson, 50, died on June 25 after suffering cardiac arrest, his family said. "I don't know what happened there. The only thing I can say is he was adamant about this drug," Ms Lee said. She said that previously she had warned Jackson against using Diprivan.

"I said, 'Michael, the only problem with you taking this medication' — and I had a chill in my body and tears in my eyes three months ago — 'the only problem is you're going to take it and you're not going to wake up," she recalled.

"He said, 'No, my doctor said it's safe. It works quick and it's safe as long as somebody's here to monitor me and wake me up. It's going to be OK,'" Ms Lee said. She said he did not give the doctor's name.

Londell McMillan, attorney for Katherine and Joe Jackson, told CNN: "I wonder why anyone would make a comment about something that they don't have much knowledge about. They didn't see the drug administered. It's again because of the Michael Jackson factor."

The Jackson family is planning to take the pop star's body to his Neverland ranch on Thursday. A public wake is planned for Friday and tens of thousands of fans are expected to attend.

The family is said to be planning a private memorial service at the remote 2,500-acre ranch in Santa Barbara County on Sunday. Plans for Jackson's funeral remain unclear.

Neverland, named after Peter Pan's island where boys never grew up, was dedicated to the pop legend's obsession with childhood. At its height, Neverland featured its own amusement park, a private zoo with giraffes and tigers and statues of children at play. Jackson left the estate after his acquittal on charges in 2005 that he molested a 13-year-old boy in 2003 at the estate.

It had fallen into disrepair but recently has been partly refurbished by a real-estate investment company that took joint ownership with Jackson last year.

Jackson left his multi-million pound estate to be held in trust for his children by his mother who is appointed as their guardian, according to reports. But the pop star left nothing to his father Joe whom he accused of abusing him as a child.

The existence of the will drafted by Jackson in 2002, emerged as his parents swiftly moved to take control of his assets in court. The Jackson family have now received a copy of the will which will be verified in court.

Jackson's former lawyer, John Branca, is named as an executor, as is veteran music executive John McClain, who was also a friend of Jackson. His parents have asked a judge to make Katherine Jackson, the star's mother, administrator of his estate.

A judge has granted Mrs Jackson, 79, temporary guardianship of Michael Joseph Jackson Jr., known as Prince Michael, 12, Paris Michael Katherine Jackson, 11, and Prince Michael II, 7. Another hearing is scheduled for Monday July 6.

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