AceShowbiz - A voicemail tape featuring Dr. Conrad Murray, which could be a key piece of evidence in his trial over the death of Michael Jackson, has been leaked. The star's personal doctor is free on $75,000 bail after he pleaded not guilty to a count of involuntary manslaughter in Los Angeles last Monday, February 8. He stands accused of administering the powerful anesthetic Propofol which killed Jackson in June 2009.

Editors at Britain's News of the World newspaper have obtained a recording of a message left by Murray on a patient's phone the morning, June 25 Jackson died - and both defense and prosecution teams are allegedly keen to use it to help their cases. Murray is heard talking calmly in the message, allegedly left at 11.54 A.M. local time - the same time Los Angeles police officials claim the doctor was attempting to resuscitate the King of Pop as he lay unconscious in his California home.

The medic's defense team reportedly wants to use the message as evidence to show cops' timing of events on the morning Jackson died is wrong - while prosecutors allegedly claim it proves Murray was evasive about his actions on the day.

A source tells the publication, "It's clear from the voicemail that Murray is not a man who sounds frantic, worried or in a stressful position. But if the police's timeline is correct, then he would have been almost an hour into giving Jackson CPR."

"Murray's lawyers know he gave Michael Propofol and understand that killed him. But just what happened in that room in those few hours Michael was last alive will be the key battleground." Murray is due to return to court on April 5, when a date for the preliminary hearing will be set.