Reports of prescription drug abuse have dogged Michael Jackson for much of his career, and now a close associate has come forward to talk about the late singer's battle with addiction.
Jackson's former video producer said the pop star, who died Thursday at age 50 from cardiac arrest, had a "20-plus year" addiction to the painkiller Demerol, as well as to a cocktail of other drugs, such as Oxycontin.
Jackson became so addicted that the video producer and other close associates tried to stage an intervention in 2003, but it derailed because of a world tour, said Marc Schaffel, who was named as an unindicted co-conspirator in Jackson's 2005 child molestation trial.
Schaffel's accusations were backed by a senior law enforcement official who told ABC that Jackson was "heavily addicted" to Demerol and received "daily doses" of Oxycontin.
Jackson even wrote and performed a song about the drug Demerol, called "Morphine," released in 1997. Both drugs are opioids.
"Everybody around him knew about it," Schaffel told ABCNews.com. "He didn't advertise it to the world, but anybody in his inner circle knew."
"I was shocked, but I knew it was only a matter of time that something like this would happen," Schaffel said. "I have said before, that if he continued using drugs at this rate, he'd be dead by the time he was 50."
Schaffel won a $3 million suit against Jackson, claiming the star failed to pay him $800,000 for his work on two television specials, and $2.3 million in payments and loans over a number of years.
The Los Angeles police were told that Jackson received a Demerol injection one hour before his death, according to a senior law enforcement official. Paramedics at the Los Angeles hospital where Jackson died Thursday, according to the British tabloid the Sun, said the star's breathing got "slower and slower until it stopped."
Medical experts speculated that drug abuse was a likely cause of death, though partial autopsy results will not be available until later today.
"Demerol may be responsible," said Dr. Christopher Gharibo, director of pain medicine at New York University Hospital for Joint Diseases. Demerol is usually administered by nurses, said Gharibo. "If the respiratory arrest occurred immediately after the Demerol injection, there was an overdose situation that either caused a seizure or respiratory depression leading to cardiac arrest."
Dr. Bruce Goldberger, chief of forensic pathology at the University of Florida, said, "Any time you have a 50-year-old man pass away in generally good hearth who's recently had a physical exam, the first thing you think about are drugs."
Primary death from cardiac arrest with this cocktail of drugs is highly unlikely unless Jackson was also using amphetamines or had a history of heart disease, according to Dr. Darin Correll, an anesthesiologist at Brigham and Women's Hospital in Boston.
The 911 audio tapes revealed that a "personal doctor" was present when paramedics were called..
"This whole thing is a little bizarre," said Correll. "You'd think that person would have been able to adequately perform CPR and stop it. If it truly was from opioids, it's easily fixed."
An overdose can be "reversible," he said, by administering mouth-to-mouth rescusitation and then an antidote -- Naloxone.