As far back as 2006, members of Michael Jackson's family were terrified that his escalating dependence on prescription drugs had become a danger to his life – and attempted an intervention in Las Vegas.
"The family believes Michael is addicted," a family insider told PEOPLE. "There was an intervention in Las Vegas. Janet was on the phone, but Randy, Jackie and Rebbie were there in person," the source said, referring to several of Michael's eight siblings.
"Michael got p---ed off. He said he wasn't on drugs. But they didn't believe him."
Jackson suffered cardiac arrest
at his rented home in Los Angeles Thursday and was pronounced dead at 2:26 p.m. PST. His autopsy will be conducted by the Los Angeles County Coroner Friday, although some tests, including a toxicology report, could take days or weeks to complete.
At the time of the Vegas intervention, another source close to the family blamed a Jackson aide for supplying the superstar with drugs from prescriptions acquired from multiple doctors.
"[The aide] has contacts wherever they are," said the source. In addition to consuming alcohol, Jackson takes "straight morphine, Demerol and opiates like Oxycontin. He also takes Valium and Xanax," said the insider.
"Michael is a clinically functioning addict and these are the most dangerous," the source continued. "They stop and start. These are the ones that OD ... It could happen any minute."
After Jackson's death Thursday, family attorney Brian Oxman, who huddled with the grieving family at the hospital, raised the possibility that the drug abuse remained a critical factor in Jackson's life. "If you think that the case of Anna Nicole Smith was an abuse, it is nothing in comparison to what we have seen in Michael Jackson's life," Oxman told CNN.
Stay tuned to PEOPLE.com for more on Jackson's cause of death ...