Authorities believe that a fatal dose of a powerful sedative given to Michael Jackson by his personal physician was the ultimate cause of the King of Pop's death last month, a law enforcement source told FOXNews.com Monday.
Speaking on condition of anonymity because of the ongoing investigation, a source also told the Associated Press that Jackson used the drug propofol reguarly to help him sleep. The King of Pop relied on the drug like an alarm clock, the source said. A doctor would administer it when Jackson went to sleep, then stop the IV drip when the singer wanted to wake up.
Shortly after midnight on June 25, the day Jackson died, Dr. Conrad Murray gave him the drug through an IV, the source told AP.
Murray's lawyer, Edward Chernoff, has said the doctor "didn't prescribe or administer anything that should have killed Michael Jackson." When asked Monday about the law enforcement official's statements he said: "We will not be commenting on rumors, innuendo or unnamed sources."
In a more detailed statement posted online late Monday, Chernoff added that "things tend to shake out when all the facts are made known, and I'm sure that will happen here as well."
Toxicology reports are still pending, but investigators are working under the theory that propofol caused Jackson's heart to stop, the official said. Jackson is believed to have been using the drug for about two years and investigators are trying to determine how many other doctors administered it, the official said.
Murray, 51, has been identified in court papers as the subject of a manslaughter investigation, and authorities last week raided his office and a storage unit in Houston. Police say Murray is cooperating and have not labeled him a suspect.
Murray became Jackson's personal physician in May and was to accompany him to London for a series of concerts starting in July.
He was staying with Jackson in the Los Angeles mansion and, according to Chernoff, "happened to find" an unconscious Jackson in the pop star's bedroom the morning of June 25. Murray tried to revive him by compressing his chest with one hand while supporting Jackson's back with the other.
The official also provided a glimpse into how the pop star was living in the weeks before he died, describing the room in which Jackson slept in his rented Beverly Hills mansion as outfitted with oxygen tanks and an IV drip. Another of Jackson's bedrooms was a shambles, with clothes and other items strewn about and handwritten notes stuck on the walls. One read: "children are sweet and innocent."
The temperature upstairs was stiflingly hot when authorities arrived at the singer's house after his death. Gas fireplaces and the heating system were on high because Jackson always complained of feeling cold, the official said.
A porcelain girl doll wearing a dress was found on top of the covers of the bed where he slept, the official said.
Police found propofol and other drugs in the home. An IV line and three tanks of oxygen were in the room where Jackson slept and 15 more oxygen tanks were in a security guard's shack, the official said.
Using propofol to sleep exceeds the drug's intended purpose. The drug can depress breathing and lower heart rates and blood pressure. Because of the risks, propofol is supposed to be administered only in medical settings by trained personnel.
The Associated Press contributed to this report.