The Los Angeles County Coroner's office has subpoenaed Michael Jackson's dermatologist, seeking "additional medical records" from the physician's Beverly Hills office, according to officials.
Craig Harvey, the coroner's chief of operations, confirmed that assistant chief Ed Winter served the subpoena at the Beverly Hills office of Arnold Klein.
Winter emerged from the dermatologist's office, where he was surrounded by reporters and photographers while stressing that Klein was cooperating with investigators.
"Dr Klein is... cooperating with us. Rumors that Dr Klein is not cooperating with us (are) not true," Winter said.
Brad Boyer, an attorney for Klein, confirmed the meeting with Winter and said his client was cooperating.
"Dr Klein has been and is continuing to cooperate with the coroner's office in their investigation," he said.
The development came as investigators were scrutinizing the possible role of drugs in the death of Jackson, 50, who died on June 25 after suffering an apparent cardiac arrest at his home in Los Angeles.
Last week, Klein denied giving Jackson a dangerous sedative -- Diprivan -- discovered at the superstar's rented mansion.
The drug is used to induce unconsciousness in hospital patients ahead of major surgery and experts say it should only be administered by a trained anesthesiologist.
Klein told CNN he was aware Jackson had used Diprivan in the past but denied he had provided it to the singer.
"I knew at one point he was using Diprivan when he was on tour in Germany," Klein said. "He was using it with an anesthesiologist to go to sleep at night and I told him he was absolutely insane."
Los Angeles coroners have deferred issuing a cause of death in Jackson's case until the results of exhaustive toxicology tests are known.

Copyright 2009 AFP American Edition