Report: Jacksons Gave Probers List of MDs

Michael's Doctor Says Jackson "At One Time Had an Addiction"

(CBS)  The Jackson family gave investigators a list of doctors who may have been over-prescribing medication for Michael, according to report on celebrity Web site TMZ.com.

The list, according to TMZ, reportedly includes Dr. Arnold Klein, Jackson's longtime dermatologist.

On CNN's Larry King Live, Klein denied unethical behavior in his treatment of the popstar.

Klein told King, "I had to keep reducing the dosage of what he was on because he came to me with a huge tolerance level."

Klein said in the same interview with King that the singer battled drug addiction and Jackson did use the drug Diprivan -- reportedly found at Jackson's home -- as a sleep aid.

"Michael at one time had an addiction," Klein said on the show. "He went to England and withdrew from that addiction in a secure setting where he went off drugs all together."

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Complete coverage of Jackson's life and death

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But what actually killed the 50-year-old King of Pop?

CBS News correspondent Ben Tracy reported on "The Early Show" Thursday the actual cause of death make take weeks to determine. The coroner's office, Tracy said, is testing tissue from Jackson's brain to see whether he had any neurological conditions, or if alleged abuse of prescription drugs may have contributed to his death.

Dr. Lawrence Kobilinsky, of John Jay College of Criminal Justice, said, "If the brain is observed as normal, then the issue becomes the toxicology report."

The toxicology report, Tracy says, could show whether prescription painkillers Jackson allegedly took, or other medications, such as Diprivan, the powerful anesthesia drug police say they found in Jackson's rented mansion, played any role in his death.