Michael Jackson Autopsy Results Expected Today

Doctors look to inform millions of fans of exactly what caused Michael Jackson's untimely death at some point Friday. (AP Images)"]

We've been told by medical and hospital staff involved in this case that Michael Jackson's shockingly unexpected death was due to cardiac arrest. However, what we don't know at this point is -- why? Did the pop icon have an undisclosed heart condition? Were prescription drugs a factor in causing his heart to suddenly stop?

Celebrity gossip website TMZ.com has a live stream of the Michael Jackson 911 tape.

The mystery surrounding Jackson's death will soon be solved as an autopsy was to begin Friday. If a cause can be determined, then Los Angeles County Coroner Investigator Jerry McKibben will make the announcement today. If toxicology tests are conducted and completed, the results may not come for another few weeks.

Was Michael Jackson dead by the time the EMT had arrived?

TMZ.com reports that Jackson's doctor was already at the scene by the time the EMT arrived. It is also believed that because all attempts to revive Jackson had failed, the EMT wanted to call his death right then and there. But it was M.J.s's doctor, cardiologist Dr. Conrad Robert Murray, who insisted they take Jackson to the hospital.

It is believed that Murray had been living with Jackson in his rented mansion. And one final note: Sister Janet Jackson has now arrived in Los Angeles.

Obviously, this tragic story is still developing...