Los Angeles ? Michael Jackson’s personal doctor administered a powerful anesthetic to help him sleep, and authorities believe the drug killed the pop singer, a law enforcement official told The Associated Press on Monday.

The official, who spoke on condition of anonymity because the investigation is ongoing, also provided a glimpse inside Jackson’s rented mansion, describing the room Jackson slept in as outfitted with oxygen tanks and an IV drip. Another of his 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 official said Jackson regularly received propofol to sleep, relying on the drug like an alarm clock. A doctor would administer it when he went to sleep, then stop the intravenous drip when he wanted to wake up. On June 25, the day Jackson died, Dr. Conrad Murray gave him the drug through an IV sometime after midnight, the official said.

Though toxicology re-ports are pending, investigators are working under the theory 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.

Using propofol to sleep is a practice far outside the drug’s intended purpose. One doctor said administering it in a home to help a person sleep would constitute malpractice.

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.”

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.