(Cover) - EN Showbiz - Dr. Conrad Murray's defence team challenged anaesthesiologist Dr. Steven Shafer's testimony, dubbing his claims "bold."

The defence took over Friday in the case against Dr. Murray for the involuntary manslaughter of Michael Jackson.

The singer died from acute Propofol intoxication in June 2009. Murray denies administering a lethal dosage of the drug to the musician.

Dr. Shafer began testifying for the prosecution on Wednesday.

The expert anaesthesiologist, who wrote the packaging insert for the powerful anaesthetic Propofol, called Murray's behaviour "unconscionable" in his testimony this week.

Jackson's death was caused by Murray's "egregious violations" of medical practice, Dr. Shafer contended.

Dr. Shafer discounted major theories proffered by Murray's defence.

The anaesthesiologist said that it was "unlikely" that Jackson injected himself with a lethal dosage of Propofol while Murray momentarily stepped out of the room.

He claimed that Murray was "utterly clueless" with medical devices and that the doctor did not have the correct monitoring equipment to treat Jackson safely.

Dr. Shafer suggested that Murray may have given Jackson more Propofol than he told authorities. Jackson had 25 additional milligrams of the drug in his system than the amount Murray reported to the police in June 2009.

Shafer also dismissed claims that Jackson died from swallowing eight tablets of Lorazepam behind Murray's back. The amount of Lorazepam found in autopsy reports was simply too "trivial" to lead to death.

Murray's attorney Ed Chernoff challenged Dr. Shafer's assertions.

"That's a bold claim, isn't it?" Chernoff asked.

"It's an honest statement," Shafer said in response.

After hours of grilling by the defence, Dr. Shafer admitted that Jackson causing his own death was a "possibility", although he made it clear that he believed the singer's demise was a result of Murray's medical negligence.

Key defence witness expert Dr. Paul White, a colleague of Dr. Shafer's for over 30 years, is expected to take the stand next week.

White was hired by the defence to conduct a separate study of Propofol ingestion on Beagle dogs. The tests proved that death could not be caused by ingesting Propofol orally, so the defence dropped this theory.

Animal rights organisation PETA has filed a complaint with the United States Department of Agriculture against Dr. White for these tests demanding that he be investigated for animal cruelty.

The trial resumes Monday. (C) Cover Media