Pop star Michael Jackson's death has been ruled a homicide from an overdose of the anesthetic propofol and other drugs, and police will refer the case to prosecutors for possible criminal charges, officials said on Friday.

The coroner's ruling fueled speculation that his doctor may face a criminal charge of manslaughter or worse.

The Los Angeles County Coroner said in a statement that propofol and the sedative lorazepam were the primary drugs responsible for Jackson's June 25 death at the age of 50.

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

Separately, the Los Angeles Police Department said its investigation was continuing but that police were referring the case to prosecutors for possible criminal charges.

Jackson, whose Thriller CD remains the best-selling album of all time, died suddenly after suffering cardiac arrest in a rented Los Angeles mansion only weeks before he was to begin a series of comeback concerts.

Houston-based doctor Conrad Murray was hired to care for the singer while he prepared for the concerts, and he was at Jackson's bedside the day he died. Murray has admitted to police that he administered propofol, which is generally used in surgery, to help Jackson sleep.

In court documents, police have said Murray is the subject of a manslaughter investigation but officials have also looked into care provided to Jackson by other doctors who may have prescribed other drugs to him.

A spokesman for Murray's lawyer said the attorney had no immediate comment.

POTENT DRUGS COCKTAIL

The list of drugs in Jackson's system reads like a cocktail of sedatives, painkillers and one stimulant. Midazolam is a sedative similar to propofol, used to make patients drowsy but not unconscious 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.

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

Forensics expert Dr. Lawrence Kobilinsky, who chairs the Department of Science at the John Jay College of Criminal Justice and is not involved in the case, said that absent the full report, it was difficult to determine whether charges would be filed against Dr. Murray and what those charges would be.

He said prosecutors would be looking 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.

If he administered a lethal dose of propofol, they could charge him with negligent homicide, Kobilinsky said.

But for now, police have only said in affidavits obtained to search Murray's office that he is the subject of an investigation for the lesser charge of manslaughter.

A spokesman for Jackson's family issued a statement on Friday saying the family commended the actions of the coroner and other law enforcement groups and looks forward to the day that justice can be served.

Medicine