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Dr. Conrad Murray gave the late Michael Jackson the powerful drug that authorities believe killed him, claims a new report.

The Associated Press, citing an unnamed official, reports that Dr. Conrad Murray allegedly gave Jackson the anesthetic propofol on the night before his death.

A law enforcement official tells the AP that Jackson had come to rely on the drug for sleep, and that a doctor would administer it intravenously to help him fall asleep -- and later stop the IV drip when he wanted to wake up.

The official also claims that on the day of Jackson's death, Dr. Murray administered the drug some time after midnight.

A lawyer for Dr. Murray tells the AP that he did not prescribe or administer anything that should have killed the King of Pop. In response to the AP report, attorney Ed Chernoff tells ET, "It's a waste of time responding to all these timed 'leaks' from 'anonymous' sources. I feel like a horse swatting flies. Everyone needs to take a breath and wait for these long delayed toxicology results. I have no doubt they want to make a case -- for goodness sakes, its Michael Jackson! But things tend to shake out when all the facts are made known, and I'm sure that will happen here as well."

Dr. Murray, who was with Jackson on the day he died last month, is also the subject of a manslaughter investigation, according to court documents cited by the AP.