Pop star Michael Jackson's death was ruled a homicide from drug overdose Friday, fueling speculation his personal physician, Dr Conrad Murray, may soon be charged with manslaughter or another crime.

The Los Angeles County Coroner said in its ruling that the powerful anesthetic propofol, which is used in surgery and has been dubbed ``milk of amnesia'' by some doctors, as well as the sedative lorazepam were the primary drugs responsible for Jackson's sudden death on June 25 at the age of 50.

Other drugs found in the singer's body were midazolam, diazepam, lidocaine and ephedrine.

Los Angeles police said they will refer the case to prosecutors for possible criminal charges when they have completed a probe into Jackson's death. In previous court filings, police have said Murray, who was with the singer the day he died, was being investigated for manslaughter.

Jackson, whose ``Thriller'' CD is the best-selling album of all time, died suddenly in Los Angeles after suffering cardiac arrest only weeks before a series of comeback concerts.

Murray, a heart specialist with offices in Houston and Las Vegas, was hired to care for the singer while he prepared for the concerts, and he was at Jackson's bedside the day he died.

The doctor previously has admitted to police that he administered propofol, which has a milky appearance and is used to sedate patients, to help Jackson sleep.

Rush to charge?

Police have looked into the activities of other Jackson doctors including his dermatologist.

On Friday the California Attorney General's office said it will begin an independent investigation of several physicians whose names have come up in the Los Angeles police probe.

Murray's attorney cautioned that the probe is not complete, nor are all the details of Jackson's death known.

“We will not be responding until we get a full autopsy report, including the entire list of drugs found in Mr. Jackson, their quantities, and all other data that would allow independent medical experts to analyze and interpret,'' attorney Ed Chernoff said in a statement.

The coroner said the complete toxicology report remained sealed at the request of Los Angeles police and prosecutors.

The list of drugs in Jackson's system provided by the coroner Friday reads like a cocktail of sedatives, painkillers and one stimulant. Midazolam, which is similar to propofol, is used to make patients drowsy during procedures such as colonoscopies.

Diazepam, the generic version of Valium, is used to calm anxiety, while lidocaine is a painkiller and ephedrine is a stimulant.

Defense attorney Steve Cron, a professor at Pepperdine University School of Law, said Murray could face up to four years in prison if convicted of involuntary manslaughter.

Forensics expert Dr. Lawrence Kobilinsky, who chairs the Department of Science at the John Jay College of Criminal Justice, said prosecutors would look at the amount of propofol and other drugs in Jackson's system, whether errors were made in administering drugs in combination, and whether Murray gave proper dosages or a lethal dosage.

Jim Cohen, a professor of law at Fordham University, said Murray could put up a vigorous defense.

“It's not an open and shut case,'' he said. ``Everyone says (propofol) can only be administered in a hospital setting. I'm sure they'll find some expert who says that's preferred, but preferred doesn't mean it's required.” – Reuters