Los Angeles ? Michael Jackson’s death has been ruled a homicide caused by a mix of drugs meant to treat insomnia, a law enforcement official told The Associated Press, while his personal doctor told investigators he was actually trying to wean the King of Pop off the powerful anesthetic that did him in.

Forensic tests found the anesthetic propofol combined with at least two sedatives to kill Jackson, according to the official, who spoke Monday on condition of anonymity because the findings have not been publicly released. Based on those tests, the Los Angeles County Coroner has ruled the death a homicide, the official said.

The coroner’s homicide ruling does not necessarily mean a crime was committed. But it makes it more likely criminal charges will be filed against Dr. Conrad Murray, the Las Vegas cardiologist who was caring for the pop star when he died June 25 in a rented Los Angeles mansion.

Doctor’s account

Through his lawyer, Murray has said he administered nothing that “should have” killed Jackson.

Murray told investigators that Jackson stopped breathing about 10 minutes after he relented and finally gave in to his patient’s demands for propofol around 10:40 a.m., following a nightlong regimen of sedatives that did not work, according to court documents unsealed Monday.

A search warrant affidavit unsealed in Houston, where Los Angeles police took materials from one of Murray’s clinics last month as part of their manslaughter investigation, includes a detailed account of what detectives say Murray told them. Man-slaughter is homicide without malice or premeditation.

The doctor said he’d been treating Jackson for insomnia for about six weeks with 50 milligrams of propofol every night via an intravenous drip, the affidavit said. Murray said he feared Jackson was becoming addicted to the anesthetic, which is supposed to be used only in hospitals and other advanced medical settings, so he had lowered the dose to 25 milligrams and added the sedatives lorazepam and midazolam.

That combination had succeeded in helping Jackson sleep two days prior to his death. So the next day, Murray told detectives, he cut off the propofol — and Jackson fell asleep with just the two sedatives.

Last morning

Then around 1:30 a.m. on June 25, starting with a 10-milligram tablet of Valium, Murray said he tried a series of drugs instead of propofol to make Jackson sleep. The injections included two milligrams of lorazepam around 2 a.m., two milligrams of midazolam around 3 a.m., and repeats of each at 5 a.m. and 7:30 a.m. respectively.

They didn’t work.

Murray told detectives that around 10:40 a.m. he gave in to Jackson’s “repeated demands/ requests” for propofol, which the singer called his “milk,” according to the affidavit. He administered 25 milligrams of the white-colored liquid — a relatively small dose — and finally, Jackson fell asleep.

Murray remained with the sedated Jackson for about 10 minutes, then left for the bathroom, the affidavit said. Less than two minutes later, Murray returned — and found Jackson had stopped breathing.

Cell phone records show three separate calls from Murray’s phone between 11:18 a.m. and 12:05 p.m., the affidavit said. It’s not clear who received the calls. Murray had told authorities he was administering CPR during that time.

In a statement posted late Monday on his firm’s Web site, Murray’s attorney Edward Chernoff questioned the timeline as depicted in the affidavit, calling it “police theory.”

“Dr. Murray simply never told investigators that he found Michael Jackson at 11:00 a.m. not breathing,” Chernoff said. He declined to comment on the homicide ruling, saying, “We will be happy to address the coroner’s report when it is officially released.”

The coroner’s office has withheld its autopsy findings, citing a request from police to wait until their investigation is complete.

‘Horrible polypharmacy’

The 25 milligrams of propofol “is not a whopping amount,” said Lee Cantrell, director of the San Diego division of the California Poison Control System. It was the cocktail of the other sedatives, known as benzodiazepines, that “may have been the trigger that pushed him over the edge,” Cantrell said.

Cantrell said it’s perplexing that someone would give various benzodiazepines if one was found not to be effective.

“This is horrible polypharmacy,” he said, referring to the interaction between the various drugs. “No one will treat an insomniac like this.”

The affidavit, signed by a judge July 20, said that the coroner’s office chief medical examiner told police his review of preliminary toxicology results showed “lethal levels of propofol.”

When he died, Jackson was skinny but not overly emaciated, and his body had bed sores, the official said. The singer is believed to have developed bed sores in the months following his 2005 acquittal of child molestation charges, when he went into seclusion and spent long stretches in bed.

Jackson’s family released a statement Monday, saying it has “full confidence” in the legal process and the efforts of investigators. It concludes: “The family looks forward to the day that justice can be served.”