Even though the toxicology results are due this week, it's not going to be easy to nail a doctor for manslaughter if it was an overdose of propofol that killed Michael Jackson, according to a pathologist all too familiar with the intricacies of toxicology.
"Propofol basically disappears [from the blood] within minutes," says Dr. Joshua Perper, the Broward County, Fla., medical examiner who spent weeks testing samples from Anna Nicole Smith's body before ruling her death the result of a prescription-drug overdose in 2007.
"Like Anna Nicole, my expectation in Jackson's case is that the toxicology would show a combination of drugs, where propofol will be present," the pathologist and author of the upcoming book When Doctors Kill told E! News.
"The problem in finding it in the body will depend on how long [Jackson] lingered before he became comatose. It breaks down very fast and can disappear or burn out in as little as two to four hours."
The longer the King of Pop lived after taking what could have been a fatal dose of propofol, the more likely it is that the evidence faded away.
Propofol can be found in other tissues, but that would make it hard to determine how much he took and whether it proved fatal and would take away a crucial piece of evidence required in prosecuting any doctor for manslaughter, much less murder, Perper said.
"To ask for more time to do testing, it stands to reason the medical examiner didn't have enough toxicology to explain the death from propofol and wants to look for something else, like a combination of drugs," he said, referring to the extra week the L.A. County Coroner's Office is taking before it releases the final autopsy report.
The main culprit in Smith's death, while she had a number of prescription drugs in her system, was the powerful sleep aid chloral hydrate.
Two of Smith's doctors and her companion, Howard K. Stern, have pleaded not guilty to felony charges of facilitating Smith with various substances.
Meanwhile, a family practitioner who has worked with nurse Cherilyn Lee, the nutritionist who says Jackson once asked her for Diprivan (propofol's brand name), tells E! News he immediately thought of Lee's story when he heard of Jackson's death.
"To be honest with you, my first reaction was 'God, I hope he didn't get that Diprivan,' " Dr. Dwight James of Porterville, Calif., said.
James said that Lee called him for more information about propofol when Jackson requested it, and that he told her it was mainly used in hospitals and wasn't the sort of thing he would prescribe a patient to use at home.
"[Lee] communicated to [Jackson] that he didn't want to use the drug because it could kill him," James said. "She took the Physicians' Desk Reference to him—it has all the indications—but he still wasn't convinced."
—Reporting by Art Harris and Lindsay Miller
Let's take a moment to remember Anna Nicole Smith.