Michael Jackson's death ruled a homicide

Michael Jackson's death has been ruled a homicide caused by a mix of drugs meant to treat insomnia, a law enforcement official says, 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 on 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 on June 25 in a rented Los Angeles mansion.

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 on 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. Manslaughter 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.

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-coloured 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.