CONTROVERSEY SURROUNDS MICHAEL JACKSONS DEATH!

The 911 caller was calm and polite but desperate.

"I need an ambulance as soon as possible, sir," he said. "We have a gentleman here that needs help, he's not breathing. We're trying to pump him but he's not breathing."

Within hours the world would find out that the unconscious "gentleman" on the bed was 50-year-old pop superstar Michael Jackson.

The identity of the caller on the 911 tape released Friday by the Los Angeles Fire Department has not been determined.

The man told a dispatcher that a "personal doctor" was at Jackson's home, a man who police want to question.

While cops have not named the doctor, a Texas TV station identified him as cardiologist Conrad Murray, who has offices in Houston and Las Vegas.

A receptionist at the Houston office confirmed to the Daily News that Murray was "on tour" with Jackson. She said the office has not been able to reach him. "He hasn't been answering his phone," the receptionist said.

Murray reportedly had been staying with Jackson while he geared up for a grueling 50-show comeback tour. Police have already impounded Murray's BMW.

"The car might contain medication or other evidence that could assist the coroner in determining the cause of Michael Jackson's death," said Officer Richard French, an LAPD spokesman.

TMZ.com reported that Jackson was already dead by the time the paramedics arrived at his rented Los Angeles mansion Thursday but that Murray insisted they try to revive him.

The EMTs found evidence Murray had been trying to resuscitate Jackson for "quite some time." A drug drug that can be used restore heart rhythms - lidocaine - was found at the scene, TMZ reported.

There was no immediate police corroboration of those claims, but an autopsy was underway on Jackson, listed as case number 2009-04415.

Among other things, investigators are looking for evidence that Jackson was abusing prescription drugs.

Wielding the knife was the chief Los Angeles County coroner Lakshmanan Sathyavagiswaran, a heavy hitter who was a star witness in the O.J. Simpson murder trial.

"Family will not be there," his spokesman, Lt. Brian Elias, told The Daily News earlier.

"It's not known if any representatives for LAPD will be there." While Jackson family insiders suggested prescription drug abuse - specifically Demerol - might have caused the superstar's heart to stop, Elias said it will be several weeks before toxicology results are ready.

Pressed on reports that Jackson died of cardiac arrest, Elias said, "Everybody's heart stops, it's very non-specific." Paramedics were called to Jackson's home at 12:26 p.m. Thursday and they worked on him for 45 minutes before rushing him to UCLA Medical Center.

There, doctors took over and tried to revive Jackson for nearly an hour before pronouncing him dead at 2:26 p.m. While Jackson suffered from a host of health problems, his addiction to prescription drugs fueled speculation he overdosed.

London's Sun newspaper reported that Jackson had trouble breathing after his morning shot of the painkiller Demerol Thursday. "He started to experience slow, shallow breathing," a source told the paper.

"His breathing gradually got slower and slower until it stopped. His staff started mouth-to-mouth and an ambulance was called which got there in eight minutes." The major hazards of Demerol, a synthetic drug similar to morphine, are breathing and circulation problems and cardiac arrest, according to the Food and Drug Administration.

Former Jackson family attorney Brian Oxman suggested injury-prone Jackson was being overmedicated as he geared up for the summer tour. "I have warned of the use of prescription medication and people who have enabled the use of those medications," Oxman said.

"I have seen it with Michael."

Jackson had been training for his soldout London concerts with "Incredible Hulk" star Lou Ferrigno.

He reportedly showed up to rehearsal at the Staples Center on Wednesday.