LOS ANGELES, California (CNN)  -- Questions swirled Friday about the possible role prescription medications may have played in the death Thursday of pop idol Michael Jackson, people close to him said.



The cause of pop star Michael Jackson's death has not been determined after Friday's autopsy.



His autopsy was completed, but further tests must be carried out before the cause of death can be determined, a spokesman for the Los Angeles County Coroner said.



Craig Harvey said the tests would take four to six weeks, after which "we anticipate being able to close the case and issuing a final cause of death." Among the tests to be carried out, he said, are neuropathology (brain) and pulmonary (lung) tests.



Harvey added, "We know that he was taking some prescription medications," but said he was not able to divulge what.



The possibility that Jackson may have been taking medication that could have contributed to his death at the age of 50 weighed heavily Friday on a number of people close to the star.  Watch coroner's office discuss Jackson's death. »



In 2005, after he was cleared on charges of child molestation, Jackson spent a week at a center run by Dr. Deepak Chopra, a physician who focuses on spirituality and the mind-body connection.



During that week, Jackson asked Chopra for a prescription for a narcotic, the doctor told CNN. "I said, 'What the heck do you want a narcotic prescription for?' And it suddenly dawned on me that he was probably taking these and that he had probably a number of doctors who were giving him these prescriptions, so I confronted him with that. At first, he denied it. Then, he said he was in a lot of pain."



Chopra said he responded to Jackson that there were plenty of other ways for him to handle his pain, but that the arguments were not persuasive.  Watch CNN's Sanjay Gupta discuss Jackson's death »



"For a while, I lost him," he said. "I have had that happen with me with other celebrities in Hollywood. There's a plethora of doctors in Hollywood, they're drug peddlers, they're drug pushers, they just happen to be having a medical license and I hope that this episode today, this tragic death of a great human being, will bring to light the huge problem we have in Hollywood with some of the medical establishment, the celebrity doctors, who not only initiate people into the drug experience, but then they perpetuate it so that people become dependent on them."



Chopra said Jackson had recently gone on a diet to prepare for his planned comeback tour, which was to have begun next month in England, and was excited about his planned resumption of his performing career.



"He was practicing, he was fasting, and yet he wasn't physically in the condition to do this, and he was not confronting his drug addiction, which is the big problem," Chopra said.



He blamed Jackson's death on drug abuse, though he offered no direct evidence. "When you have enough drugs in your system, your heart goes into an arrhythmia and your respiration stops," he said. "I think the drugs killed him."



Chopra said he had known Jackson to take the opium-derived painkiller OxyContin at one time, as well as injections of the narcotic pain reliever Demerol "and other narcotics, and I was really desperate to try to help him, but you know you can't help somebody who would go into denial."  Watch crowds gather at the hospital. »



Jackson typically would refuse to call Chopra for several weeks at a time, the doctor said. "Then he would call me two or three weeks later and say he was sorry, that he had been busy and it wasn't the drugs -- but it was the drugs."



Chopra, who said he knew Jackson for more than two decades, described him as "my little brother -- I feel very bad for him."



Brian Oxman, a former
What spokesman said about Jackson`s death? What caused the death to "King of Pop" comparing to Deepak Chopra? what does chopra believe Who believes prescription drugs killed the "King of Pop?" What did the spokesman say?
further tests must be carried out before prescription medications "I think the drugs killed him." a number of people His autopsy was completed, but further tests must be carried out before the cause of death can be determined,
question: What spokesman said about Jackson`s death?, answer: further tests must be carried out before | question: What caused the death to "King of Pop" comparing to Deepak Chopra?, answer: prescription medications | question: what does chopra believe, answer: "I think the drugs killed him." | question: Who believes prescription drugs killed the "King of Pop?", answer: a number of people | question: What did the spokesman say?, answer: His autopsy was completed, but further tests must be carried out before the cause of death can be determined,