Jackson's doctor investigated

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US federal authorities have searched the Las Vegas home of Michael Jackson's doctor, and visited his surgery as part of a manslaughter investigation into the singer's death.

Michael Jackson (File photo)

Several Drug Enforcement Administration agents entered Dr. Conrad Murray's sprawling home, accompanied by uniformed Las Vegas police. Police also entered Murray's medical offices in Las Vegas. Murray was one of Michael Jackson's doctors and was with Jackson when he died. Police say Murray is cooperating and they have not labelled him a suspect.

Toxicology reports are still pending, but investigators are working on the theory that the anaesthetic propofol caused Jackson's heart to stop. Jackson is believed to have been using the powerful drug for about two years.