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Los Angeles (CNN) -- Michael Jackson "clearly" suffered from insomnia that could have been caused by Demerol, a narcotic he was getting frequently from a doctor other than Dr. Conrad Murray, according to a sleep expert testifying Thursday in Murray's involuntary manslaughter trial.
Murray's defense team contends Dr. Arnold Klein injected Jackson with 6,500 milligrams of Demerol during visits to his Beverly Hills, California, dermatology clinic in the last three months of his life, and that Murray did not know about it.
Jackson desperately sought sleep the day he died, worried that without rest he could not rehearse that night, which could force the cancellation of his "This Is It" comeback concerts, according to Murray's interview with police.
Soon after he found sleep, Jackson suffered respiratory arrest and was later declared dead by an emergency room doctor at Ronald Reagan UCLA Medical Center in Los Angeles.
Dr. Nader Kamangar, a UCLA sleep expert testifying for the prosecution, said medical records indicated Jackson's insomnia could be related to "anxiety for performing, as well as use of drugs, medications such as Demerol."
Klein was never charged or disciplined for his treatment of Jackson, but Murray's lawyers contend that treatment addicted Jackson to Demerol and caused the insomnia that Murray was treating when Jackson died.
Murray claimed the day Jackson died he was trying to wean Jackson from using the surgical anesthetic propofol to induce sleep, a treatment he gave him almost every night the previous two months.
Murray told detectives that during the last morning he gave Jackson a series of three sedatives -- Valium, lorazepam and midazolam -- over a 10-hour period before finally giving in to Jackson's plea to again use propofol.
"I've got to sleep, Dr. Conrad," Murray said Jackson pleaded to him. "I have these rehearsals to perform. I must be ready for the show in England. Tomorrow I will have to cancel my performance, because you know I cannot function if I don't get to sleep."
Kamangar said the combination of drugs Murray gave Jackson "was the perfect storm" that killed him.
"Mr. Jackson was receiving very inappropriate therapy, in the home setting, receiving very potent sedatives, including propofol, lorazepam and midazolam, without monitoring by Murray, and ultimately this cocktail was a recipe for disaster," Kamangar said.
The trial "will be, in all likelihood, concluding a lot earlier than we expected," Los Angeles County Superior Court Judge Michael Pastor said at the start of the 12th day of testimony Thursday. Lawyers previously estimated it would conclude around October 28.
While there will be no court Friday to allow the prosecution's expert anesthesiologist, Dr. Steven Shafer, to attend a medical convention, the end of testimony could come next week.
Dr. Shafer briefly began his testimony Thursday morning before the trial was adjourned. The judge agreed to let Shafer leave for the conference in Chicago where he will present a paper on propofol.
He is expected to be the next and last witness for the direct presentation of the prosecution's case against Murray.
Shafer's testimony is expected to echo the opinions of Kamangar and Dr. Alon Steinberg, a cardiologist who testified Wednesday, that Murray's treatment of Jackson was so grossly negligent that it was criminal.
Murray's delay in calling 911 for help as soon as he realized Jackson was not breathing may have cost the pop icon his life, Steinberg testified.
He and Kamangar both presented a long list of what they said were instances of Murray's extreme deviation from the standards of medical care, including his failure to immediately call for paramedics.
"If these deviations would not have happened, Mr. Jackson would be alive," Steinberg testified.
The Los Angeles County coroner ruled that Jackson's June 25, 2009, death was from "acute propofol intoxication" in combination with several sedatives, including lorazepam.
Murray's lawyers contend that Jackson used a syringe to inject the fatal overdose through a catheter on his left leg while Murray was away from his bedside. They dropped the theory pushed earlier that Jackson may have orally ingested the propofol that the coroner says killed him.
Murray's defense also contends that Jackson swallowed eight tablets of lorazepam, a sedative, in a desperate search for sleep the day he died.
Murray should be found guilty even if jurors accept the theory that Jackson self-administered the fatal dose because the doctor was reckless in leaving propofol and lorazepam near his patient when he was not around, Steinberg testified.
"It's like leaving a baby that's sleeping on your kitchen countertop," Steinberg said. "There's a very small chance the baby could fall over, or wake up and grab a knife or something."
Steinberg said he based his conclusions on Murray's own words to detectives in an interview two days after Jackson's death. That interview was played for jurors in the previous two days of the trial.
Jackson would be alive today if Murray had called 911 for help within two minutes of realizing Jackson was not breathing, instead of waiting about 20 minutes before asking a security guard to call, Steinberg said.
Earlier testimony revealed Murray did ask Jackson's chef to send a security guard upstairs to help him about five minutes after the time prosecutors suggest he realized there was a problem with Jackson. The chef, however, testified that she sent Jackson's 12-year-old son upstairs instead of security.
Steinberg said the use of propofol to treat Jackson's insomnia was another extreme deviation from standards that contributed to Jackson's death. He later acknowledged a recent report from China that the anesthetic had been successfully used to treat chronic insomnia, but he suggested it needed more study to be accepted.
Kamangar, the sleep expert, testified that propofol has no therapeutic value in treating insomnia, and to use it is unethical and an extreme deviation from the standards of care.
"It is beyond comprehension," Kamangar said. "It is frankly disturbing."
Steinberg said he based his conclusions on his belief that Murray had connected Jackson to an IV drip of propofol after he gave him an injection of propofol. That assumption, he said, was made because Murray told police he had used such a drip on most previous nights.
When Flanagan challenged him to show where in Murray's police interview he said he used a drip the day Jackson died, he eventually said "I will agree with you, it's not completely clear."
Murray said he injected a small dose of propofol using a syringe, but the prosecution contends he also used a makeshift IV setup to keep Jackson medicated and asleep. That drip may have malfunctioned while the doctor was not monitoring his patient, they contend.
The prosecution has been unable to produce the tubing that would be a critical piece of an IV system, although they did show jurors an opened saline bag into which they contend Murray placed an opened propofol bottle.
On the recording, Murray insisted he kept a close watch on Jackson after he finally fell asleep. The physician never mentioned the long list of e-mails and calls that cell phone records later revealed.
Murray was hired as Jackson's personal physician while the singer prepared for his "This Is It" comeback concerts in London, planned to start in July 2009.
If convicted of involuntary manslaughter, Murray could spend four years in a California prison and lose his medical license.