Police believe that Michael Jackson's personal physician killed him by administering a powerful drug, according to reports.

Dr Conrad Murray gave the pop star the anaesthetic propofol the night before he died, an unnamed law enforcement official told the Associated Press.

Jackson was regularly given propofol to help him sleep. The drug, also known as Diprivan, is used to induce unconsciousness in hospital patients before major surgery. Reports have said that it was found in Jackson’s home.

Dr Murray, 51, has been a central character in the investigation from the outset - Jackson's family have long accused Dr Murray of having a hand in his death.

The cardiologist was with Jackson when he died on June 25 and has been identified in court papers as the subject of a manslaughter investigation. Dr Murray's lawyer has said the doctor did not prescribe or administer anything that should have killed the pop star.

The personal physician, who had been treating Jackson for three years and had recently moved into his rented mansion in preparation for travelling to London with him for a series of concerts, desperately tried to revive Jackson when he found him unconscious at his home.

Police officers and federal drug agents have searched the doctor's offices under a warrant allowing authorities to seek "property or items constituting evidence of the offence of manslaughter that tend to show that Dr Conrad Murray committed the said criminal offence".

Court documents detailed items seized by federal drug agents and Los Angeles police. Among them were 27 tablets of the weight loss drug phentermine, a tablet of the muscle relaxant clonazepam, two computer hard drives, e-mails and a controlled substance registration document. Dr Murray is licensed to practice in California, Texas and Nevada.

No official cause of death has been given for Jackson pending toxicology reports ordered by the Los Angeles coroner but they should be available later this week. Investigators have also reviewed medical records taken from the offices of other doctors in the probe.

Dr Murray has kept a low profile since Jackson's death. He was interviewed twice by police but has not spoken publicly. Doors to his Las Vegas office have remained locked with curtains drawn behind them.

Times Recommends

• Times Charity Appeal: SolarAid
• Is it Black Monday all over again for Dubai?
• Behind the scenes at the biggest deal