After gathering information about what was prescribed and in what quantity, investigators with medical training look at the patient's history, the possible reasons each drug was prescribed, the side effects and the interactions with other medications. Investigators must also cross-reference files to try to recreate what a physician knew at the time he or she wrote a prescription.
Ed Winter, assistant chief of the coroner's office, said the office does send subpoenas out in death investigations. "In many cases doctors will hand over the records," he said. "In some cases they will ask us for a subpoena to get those records."
Winter would not comment on whether subpoenas were issued in Jackson's death. Authorities have stressed that it's too early to know whether any crimes have been committed and that much depends on the official cause of death.
While officials are awaiting the results of toxicology tests conducted by the coroner's office the day after Jackson's death, they warn that those tests may not answer all the questions. For example, sources have told The Times that detectives found large amounts of the powerful anesthetic Diprivan at Jackson's home. But experts said that the drug moves through the body quickly and might not show up in some tests.
It's an extremely potent drug that is supposed to be dispensed by a person trained to administer anesthesia.
Paul Wischmeyer, an anesthesiologist at the University of Colorado who co-wrote a 2007 study of Diprivan abuse for the journal Anesthesia & Analgesia, said that Diprivan would be "probably undetectable" in the bloodstream in 20 minutes after a single dose.
But he said that there are other ways that pathologists have used to identify the presence of the drug in autopsies, if they know what to look for.
In an interview with Larry King on Wednesday, Klein said that Jackson was using Diprivan "when he was on tour in Germany." It's unclear exactly when that was, but the last time Jackson was on tour in Germany was 1997.
Klein said that Jackson "was using it, with an anesthesiologist, to go to sleep at night. And I told him he was absolutely insane. I said you have to understand that this drug, you can't repeatedly take. Because what happens with narcotics, no matter what you do, you build a tolerance to them."
Wischmeyer disputed that, saying that he had never observed a person building up tolerance to the drug, nor had he seen any such reports in the descriptions from abusers.
