Nov. 4, 2011 -- The involuntary manslaughter trial of Dr. Conrad Murray, the cardiologist accused of causing the death of Michael Jackson, has offered a glimpse of the pop icon's secret world -- one dominated by powerful prescription drugs that ultimately claimed his life.
In Murray's trial, the prosecution argued that the array of drugs that Murray prescribed Jackson -- the anesthetic propofol, as well as the pre-anesthetic drug midazolam and lorazepam, an anti-anxiety drug -- and Murray's failure to properly monitor his patient was a recipe for disaster.
Jackson died on June 25, 2009, after receiving a fatal dose of propofol.
The defense claimed that Jackson injected himself with the lethal dose and that Murray had been trying to wean Jackson off of propofol. He prescribed it, lawyers said, to combat Jackson's insomnia, which, the defense said, was a side effect of Jackson's prior dependence on the narcotic painkiller Demerol.
Jackson used to be injected with that drug by his dermatologist, Dr. Arnold Klein, during painful dermatology treatments and, perhaps, by others.
Klein told ABC News' Jim Avila that redacted medical records presented during Murray's trial about Jackson receiving Demerol were not his records, though he conceded that he gave Jackson Demerol.
However, he added, it would be "nonsense" to believe Jackson was dependent on the drug.
"He was never addicted to narcotics," Klein said. "People have drugs of choice, sir. His choice was propofol."
Klein called propofol a "highly dangerous" drug that should not be used for sleep.
"But, unfortunately, when you're at that level of wealth, doctors will do anything for you," Klein said. "So I'm just telling you that this has been a long problem."
While it was barred from being discussed at Murray's trial, Jackson's issues with prescription drugs and enabling doctors went back years.
"He was getting a number of different prescriptions from a number of different names," said spiritual guru and former endocrinologist Deepak Chopra, a friend of Jackson's. "This is a common thing amongst celebrity addicts because they demand what they want and there are certain kinds of doctors who will give it to them."
Frank Cascio, a longtime friend of Jackson's, said the singer was like a father to him. But in later years, Cascio said, he took it upon himself to keep Jackson's enabling doctors at bay, as he describes in his book, "My Friend Michael," which will be published Nov. 15.
"Don't get me wrong. There were some great doctors," Cascio said. "There were some doctors that were absolutely fantastic."
But then there were, as Cascio calls them, the "random people" -- doctors, he said, who saw Jackson as "a money pit."
"They were just selfish, disgusting doctors that knew they would get paid," Cascio said. "They would, like, push [medications] on him because they knew he would pay them."
As a teen, Cascio was on tour with Jackson with Mexico City in 1993 when Jackson was swept off to rehab by his good friend, screen legend Elizabeth Taylor.
"Elizabeth takes us aside and says to us, 'We're going to get him out of the country after the show. He's going to go to London,'" Cascio remembered.
Jackson would later release a videotaped statement to his fans, announcing he had undergone "treatment for a dependency on pain medications."
Years later, Cascio began working for Jackson. He said he would keep Jackson's stashes of the anti-anxiety drug Xanax, the narcotic painkiller Percocet or the sedative Valium out of Jackson's reach at night.
"I wanted to always make sure I had them with me and not have anything in his room where he didn't wake up and say, 'I can't sleep tonight,' and not realize what he's taking. I was trying to think 10 steps ahead," Cascio said.
Jackson, he said, resorted to certain medications when he "just wanted to escape all the chaos."
Cascio said the drug he worried about most was Demerol.
"I didn't like what it did to him at all," Cascio said. "There was a change in personalities, especially when you saw him coming down from it and, you know, he became a different person."
Cascio said Jackson became angry, bitter and "mad at everyone just taking advantage of him."
"That's not a person that I was very fond of," he said. "That's not a person that I know that he wasn't fond of."
In November 2000, Cascio said, a house doctor at a New York City hotel was all too willing to provide Jackson with meds.
"The house doctor gave him what he wanted," Cascio said. "And, again, the house doctor was in awe and so intrigued just to be around this man."
Cascio confronted Jackson, but to no avail.
"I said, 'You don't want to end up like Elvis, do you?' And [he said] 'I would never end up like Elvis. I don't have a problem,'" Cascio said. "He was upset that I would even bring this up and talk to him about this."
Jackson's sister, Rebbie Jackson, and brother, Tito Jackson, said earlier this week that they too tried to get through to Jackson. Tito Jackson said his brother's security team got in the way.
"I got into physical fights with his security team," he said. "The public didn't know, but we did many times try and they kept him away like he was the president of the United States."
Cascio described Michael Jackson as a "situational addict."
In the weeks leading up to his death, that addiction seemed to include propofol, also known as Diprivan, a powerful anesthetic injected intravenously, often used to sedate patients before surgery.
Chopra remembered Jackson asking him about the drug.
"On one occasion ... he said to me, 'Deepak, did you know there's something that takes you right to the edge, to the valley of death, and it brings you back? Do you know anything about it?'" Chopra said.
On May 12, 2009, Murray put in a staggering bulk order for propofol -- more than 40 gallons worth. Jackson died some seven weeks later after receiving a fatal dose of the drug.
"It was a pharmaceutical experiment on Michael Jackson," prosecutor David Walgren said during his closing argument on Thursday. "It was an obscene experiment in 2009 done by a doctor with no sleep medicine training. It was criminal gross negligence."
Many music legends have died from accidental drug overdoses, but only Michael Jackson had a doctor by his side.
Cascio, who believes Murray should be in jail, said Jackson once confided in him that he feared he would die from a gunshot. But, Cascio said, no one would have ever thought that a shot of a prescription drug would claim Jackson's life so prematurely.
ABC News' Christina Ng contributed to this report.