Tempers Flare During Jackson Doctor Trial

Lawyers for Conrad Murray have dramatically challenged a key prosecution witness over his claim that the doctor was responsible for the death of Michael Jackson.

Dr Steven Shafer has testified that the only plausible explanation for Jackson's death was that he had been hooked up to a drip of the anaesthetic propofol, then left alone by Murray.

In cross examination, Murray's lawyer Ed Chernoff asked Dr Shafer: "That's a bold claim, isn't it?"

Dr Shafer replied: "It's an honest statement."

Mr Chernoff also questioned the Columbia University researcher and professor about his demonstration of IV equipment for jurors on Thursday.

He suggested Dr Shafer had drawn conclusions that were not necessarily supported by the evidence.

In a bad-tempered exchange, Mr Chernoff asked Dr Shafer if he understood the difference between opinion and fact.

Mr Chernoff asked: "You understand everything you said in the last few days was an opinion, right?"

Dr Shafer replied: "I think I stated my name, which is a fact."

Earlier Dr Shafer had admitted it was possible Jackson had opened a clamp to release a dose of drugs into the IV line but that Murray would still be responsible for not staying with his patient.

Murray has pleaded not guilty to involuntary manslaughter. He faces up to four years in prison and the loss of his medical licence if convicted.

He had been Jackson's personal doctor as the star prepared for a series of comeback concerts at London's O2 arena. He was with Jackson when he suffered a fatal cardiac arrest in June 2009.

Dr Shafer, an expert on propofol, told jurors earlier this week that his explanation was supported by items found in Jackson's bedroom, the singer's post-mortem examination results and Murray's lengthy statement to police.

In a separate development, outside of the presence of the jury, judge Michael Pastor has ordered the defence's own propofol expert to face a hearing over whether he breached a court gagging order by speaking to a reporter.

Dr Paul White, who has known Dr Shafer for 30 years, was reported to have criticised both him and the prosecutor David Walgren while speaking to a TV network.

The defence is expected to call its first witness on Monday as the trial enters its fifth week.