Michael Jackson's dermatologist says he on occasion gave the pop star the painkiller Demerol but warned him about using the powerful sedative Diprivan.

Dr. Arnold Klein tells CNN's "Larry King Live" that Demerol was among the strongest drug he prescribed Jackson and doesn't know how he got Diprivan, usually administered by anesthesiologists in hospitals.

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Investigators looking into the cause of Jackson's June 25 death have homed in on drugs given the insomniac musician. Diprivan was allegedly found in Jackson's home.

The dermatologist says: "If you took all the pills I had given him in the last year at once, it wouldn't do anything to you."

Klein said Wednesday he discovered that Jackson was using Diprivan while on tour in Germany. Klein told Jackson the drug was dangerous: "I told him he was absolutely insane."