Oct. 15 (Bloomberg) -- The three months Los Angeles Police have spent investigating Michael Jackson’s death by drug overdose highlight the difficulty of the case they are trying to construct against his doctor, Conrad Murray.

“These are very hard cases to make,” said George Annas, chairman of Boston University’s Department of Health Law, Bioethics & Human Rights. “It’s very, very, very rare for a physician to be tried for murder or manslaughter. It’s got to be really egregious, something no other physician would do, and it would have to be wanton and willful misconduct.”

Murray would be among the few doctors charged with homicide in a patient’s accidental death if he is formally accused of causing the singer’s drug overdose, according to Annas, who has written on the subject in the New England Journal of Medicine.

Investigators have yet to present their findings to prosecutors, said Sandi Gibbons, a spokeswoman for the district attorney. Detectives are investigating possible manslaughter charges against Murray, 56, according to court documents. He became Jackson’s physician as the pop singer prepared for a series of comeback concerts in London this year.

Police spokeswoman Officer Sara Faden said on Oct. 12 “the investigation is ongoing” and to her knowledge, hadn’t reached a conclusion. Jackson died June 25 at his home in Los Angeles. On Aug. 28, the coroner ruled Jackson’s death a homicide, concluding he died at the hands of another.

Cases against doctors usually involve allegations of intentional harm, quackery or extreme medical negligence, according to John Gill, deputy chief medical examiner for Bronx County in New York. Euthanasia, botched abortions, elder abuse and neglect are types of cases that may lead to charges. Few states keep statistics on the subject, he said.

Taking Their Time

Ed Chernoff, Murray’s attorney, said in an interview that investigators are rightly taking their time.

“The issue that the prosecution is being thoughtful about is whether or not he did something that rises to the level of criminality, and our view has always been that it did not,” Chernoff said.

A search warrant filed in Houston, where Murray once practiced and maintained a storage unit, sought “property or items constituting evidence of the offense of manslaughter that tend to show that Dr. Conrad Murray committed the said criminal offense.”

If prosecutors don’t find evidence of malice or intent to kill and still want to pursue a homicide case, involuntary manslaughter would be most likely, said Jean Rosenbluth, a former federal prosecutor who teaches law at the University of Southern California.

Convincing Jurors

Prosecutors would have to convince jurors that Murray was grossly negligent, acting with “such recklessness that he knew or should have known that death or great injury would occur,” Rosenbluth said.

In prescription drug overdoses, doctors are more likely to face narcotics charges, particularly if patients took the pills themselves rather than being injected or treated intravenously as Jackson was, Rosenbluth and Annas said.

Sandeep Kapoor and Khristine Eroshevich have pleaded not guilty in California to charges they illegally prescribed controlled substances to former Playboy model Anna Nicole Smith, who died of a drug overdose in a Florida hotel in February 2007.

Jackson’s death certificate says he died of “acute propofol intoxication” from “intravenous injection by another,” with anti-anxiety drugs contributing.

911 Call

Propofol is used to anesthetize patients in hospitals, clinics and dental offices, according to the manufacturer, AstraZeneca Plc, the Physicians’ Desk Reference, and the American Society of Anesthesiologists. It isn’t approved by the Food and Drug Administration for the treatment of insomnia at home, as Jackson, 50, had used it.

The day Jackson died, Murray told paramedics who responded to a 911 call and the emergency room doctor that he administered Lorazepam (Ativan), an anti-anxiety benzodiazepine, to Jackson intravenously to help him sleep, according to the search warrant. Two days later, Murray said “he had administered 25 mg of propofol along with Lidocaine to Jackson intravenously,” the warrant says, after other sedatives didn’t work.

Murray also told police he tried to wean Jackson from propofol, which other doctors also gave the entertainer, and withheld the treatment for a few nights before his death.

The doctor estimated Jackson stopped breathing at 11 a.m. June 25 and said he called for an ambulance at 12:22 p.m., according to the warrant. Murray’s cell phone records show three calls totaling 47 minutes from 11:18 a.m. to 12:05 p.m. that he didn’t report to police, the warrant said.

Chernoff disputed the timeline police say Murray gave for the sequence of events.

Self-Policing

Most deaths involving medical error or negligence occur in a hospital or clinic and never come to the attention of police or prosecutors, said Gill, the Bronx medical examiner who co- wrote “Medical Homicide and Extreme Negligence” in The American Journal of Forensic Medicine and Pathology in March.

“The person making the mistake is the one reporting the death,” Gill said. “Typically, the results are reported as suspected or known complications.”

In Los Angeles, 90 deaths were attributed to therapeutic accidents in 2006, according to the coroner’s latest annual report. There were a total of 1,098 deaths labeled homicides, and all but 22 involved firearms, blunt trauma, sharp force, strangulation or arson.

Gibbons, a spokeswoman for the district attorney for two decades, said she couldn’t recall any physicians prosecuted for murder or manslaughter in recent years.

Police, Paramedics

In Jackson’s case, paramedics and police were involved. The coroner’s office was summoned to the hospital and detectives assigned to assist in an investigation. Murray refused to sign the death certificate, according to the search warrant.

Medical examiners in most states categorize deaths five ways: as a homicide, suicide, accident, natural or undetermined, in accordance with World Health Organization guidelines, according to John Howard, president of the National Association of Medical Examiners. New York is among the few states with a separate category for medical negligence, said Gill.

Most cases involving so-called medical or therapeutic causes are categorized as natural or accidents by coroners, Howard said in an interview.

Steven Heimberg, a Los Angeles lawyer and doctor who tries cases on behalf of plaintiffs who are paralyzed or dead due to alleged medical errors, says it’s difficult to determine the real circumstances of unexpected deaths and injuries that occur under a doctor’s care.

“Even with the eyes of the planet focused on the Michael Jackson case, it’s taken weeks for what happened to come out,” Heimberg said. “Think how much investigative time and reporting it took to get that sort of thing exposed, even with the world watching.”

To contact the reporters on this story: Valerie Reitman at valeriereitman@gmail.com; Edvard Pettersson in Los Angeles at epettersson@bloomberg.net.

Last Updated: October 15, 2009 00:01 EDT