United States drug enforcement agents and police have searched the Los Angeles offices of Michael Jackson's doctor.
Conrad Murray's lawyer says they were looking for evidence of possible manslaughter in the 50-year-old singer's death on 25 June.
The Los Angeles coroner's office has yet to release the results of a toxicology report.
Police were reportedly acting on preliminary post-mortem results suggesting that one or more drugs found in lethal amounts in Jackson's system came from Dr Murray's office.
Dr Murray was at the singer's Los Angeles mansion when he collapsed and died after suffering a cardiac arrest. He tried to perform CPR before calling emergency staff.
The doctor's lawyer has denied that Dr Murray administered painkillers that could have contributed to Jackson's death and says that any drugs prescribed were in response to a specific health complaint.
Dr Murray has not been named as any type of criminal suspect and his lawyer says the doctor did nothing wrong.
