Los Angeles - Police and federal agents on Wednesday raided the Houston offices of Dr. Conrad Murray, the physician who was with Michael Jackson when the entertainer died suddenly of cardiac arrest last month.

Though the results of a coroner's report are yet to be released, attention is focused on the hospital anesthetic Propofol, a hospital anaesthetic usually administered intravenously which can easily cause cardiac arrest if not properly administered.

Jackson, a long-time insomniac, is believed to have used the drug to sleep, and the suspicion is that Murray administered it to him, People magazine reported.

"It is Conrad Murray they're looking at," the magazine quoted a source as saying. "They are looking for Propofol, along with anything else they find. But Propofol is the big one."(dpa)