Michael Jackson's doctor could either be cleared of the star's manslaughter or found guilty over the same piece of evidence.

Both the prosecution and the defence have submitted a voicemail left by Dr Conrad Murray – the last person to see Michael alive – on the day of the late Thriller singer's death on June 25 last year.

The defence will argue that the call, according to police reports left at 11.54am, shows Conrad wasn't in a frantic state trying to administer emergency life saving rescusitation to Michael – who died from an overdose of anaesthetic Propofol - at the time.

The prosecution will, however, say the call was made as Michael lay unconscious or already dead at his rented Hollywood home, and Conrad was either not in the room when Jackson passed away or not paying attention to his patient's needs.

In the message, to another patient, Conrad sounds calm as he says: 'This is Doctor Murray, Bob. Hi, how are you? Sorry I missed you. Just wanted to talk to you about your results of the EECP.

'You did quite well on the study. We would love to continue to see you as a patient even though I may have to be absent from my practice for, uh, because of an overseas sabbatical.'

Conrad's lawyers will claim the Police's timeline is incorrect and use the message as evidence pointing towards the police bungling their inquiry into Michael's death – thus discrediting early interviews with Conrad by the Los Angeles Police Department.

A source told the News of The World newspaper: '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."

Conrad – who has pleaded not guilty to a charge of involuntary manslaughter – claims he administered Michael with Propofol, then went to the toilet for around two minutes, and upon returning found the star wasn't breathing.

Records submitted to the court claim the doctor was on his mobile phone for 47 minutes between 11am and midday, while an emergency call from one of Michael's bodyguards was made at 12.21.

The District Attorney's Office say Conrad never informed them of these calls, which could work in the prosecution's favour.

Another source said: 'The fact that Murray made this call and didn't tell the police about it may be useful to the prosecution.

"Basically, it shows he was being evasive and had something to hide. Why would you not tell the police about every single thing you had done during those crucial moments when Michael Jackson was dying?"