Michael Jackson's Cause of Death Unclear, Additional Tests Needed: Coroner

June 26, 2009 — -- Clues about the underlying cause of the death of pop icon Michael Jackson are still in short supply -- and likely will remain so for several weeks, according to forensic pathologists.

The Los Angeles County coroner's office announced it concluded Jackson's autopsy at 4 p.m. PT today, but the determination of the cause of the pop star's death has been deferred because the medical examiner ordered additional toxicology, neuropathology and pulmonary tests.

Craig Harvey, operations chief of the L.A. County coroner's office, said the tests will take four to six weeks to complete, at which time he anticipates being able to issue a final cause of death.

Harvey added that the coroner found "no indication of any foul play on the body of Mr. Jackson."

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But according to a senior law enforcement official briefed on the initial investigation of Jackson's death, it's probable drugs played a part. He told ABC News that Jackson was "heavily addicted" to the powerful pain killer Oxycontin and received "daily doses" of it and of another pain killer, Demerol.

The Los Angeles police were told Jackson received an injection of Demerol one hour before his death, the official added.

Los Angeles Police Deputy Chief Charlie Beck said Friday in a press conference that the robbery/homicide division has been in contact with Conrad R. Murray, the doctor present at Jackson's home when 911 was alerted.

Delays of several weeks between the death of a celebrity and the release of their final autopsy report are not uncommon, as seen in the past.

There are many factors that can contribute to this delay, not the least of which is the fact that while preliminary tests of blood and urine can often be performed quickly, other processes can take more time.

"The preliminary results will be available early -- within 48 hours -- for many substances; however, other levels may be sent to other laboratories with required analytical capabilities that will need time to run specific assays," said Dr. Christopher Holstege, director of medical toxicology and the University of Virginia in Charlottesville. "That could take weeks depending on the priority that is being placed on those samples."

Teasing out the exact levels of each of the possible drugs involved could also require more extensive testing. In Jackson's case, because pain medications may have been involved, the possibility that the interactions between multiple drugs is a distinct one, noted Dr. Paul Christo, director of the Pain Treatment Center at Johns Hopkins Hospital in Baltimore.

"If you are on multiple medications ... if you combine these medications and take any one in excess, then that can tip you over the point where you lose the ability to breathe well," Christo said. He added that if Jackson happened to be taking alcohol at the time as well, it could magnify this effect.