BEIJING, July 2 (Xinhuanet) -- The U.S. Drug Enforcement Administration joined the investigation into Michael Jackson's death at the request of the L.A. Police Department, said media reports Thursday.    

    The federal agency can provide resources and experience in investigating drug abuse, illicit drug manufacturers known as "pill mills" and substances local police may not be familiar with, because of the sensitivity of the ongoing investigation, an anonymity official said.

    The DEA would likely play a role in looking at Jackson's doctors, the drugs they prescribed and whether the doctors were registered with the DEA to prescribe those substances as federal law requires.

    Also, investigators are expected to look at the sources of the drugs provided to Jackson or his associates to determine if there was a pattern of trafficking.

    Authorities removed prescription medications and two bags of "medical evidence" from his Holmby Hills home where the pop star was found dead last Thursday. Investigators are also interviewing doctors who treated Jackson and prescribed him medication. It remains unknown whether prescription drugs played a role in Jackson's death.

    An autopsy performed Friday did not determine a cause of death, and the coroner's office is awaiting the results of toxicology tests.

    (Agencies)