According to The Sun, a source in the emergency room at UCLA hospital said Michael Jackson's aides told medics he had collapsed after taking an injection of Demerol, a strong painkiller similar to morphine.

"Shortly after taking the Demerol he started to experience slow shallow breathing. His breathing gradually got slower and slower until it stopped," said the source.

"His staff started mouth-to-mouth and an ambulance was called which got there in eight minutes - but found he was in full respiratory arrest, no breathing and no pulse. They started full CPR and rushed him to hospital.

"When he arrived they started resuscitation, giving him heart shocks and inserted a breathing tube and other supportive measures to try and save his life.

"He never regained consciousness. The family was told that he had passed."

What is Demerol? According to Wikipedia, Demerol is also known as pethidine or meperidine. It is used for acute pain relief and is considered safer than morphine. It has serious side effects when used with antidepressants and alcohol. It is considered to be one of the drugs David Kennedy, son of Robert F. Kennedy, and Tammy Wynette were addicted to and using heavily around the time of their deaths.