Los Angeles (CNN) -- Round two of the battle of the propofol experts started Thursday afternoon in the trial of Michael Jackson's doctor as the defense anesthesiology expert began his testimony. When Dr. Paul White continues his testimony Friday, and he is expected to counter the conclusions of prosecution anesthesiologist Dr. Steven Shafer, whose earlier testimony spanned more than a week of Dr. Conrad Murray's involuntary manslaughter trial. Dr. White said that after reviewing the reports, evidence and analysis from investigators in Jackson's death he was not convinced Dr. Murray was responsible. "I was somewhat perplexed at how a determination has been made that Dr. Murray was infusing propofol," White said. "It wasn't obvious to me, I thought there were questions."
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NEW: Defense expert "perplexed" by investigator's conclusions
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Addiction specialist testifies Jackson was "probably addicted" to Demerol
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Demerol withdrawal could've caused Jackson's insomnia, expert says
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Jury deliberations in Murray's involuntary manslaughter trial could begin early next week
While @placeholder was not found in Jackson's blood or body during his autopsy, the defense contends it played a major role in his death.