LOS ANGELES - Michael Jackson's personal physician pleaded not guilty on Tuesday to a charge of involuntary manslaughter two weeks after he was ordered to stand trial for his role in the pop star's 2009 death.

Doctor Conrad Murray, the late Michael Jackson's personal physician, listens during his arraignment on a charge of involuntary manslaughter in the pop star's death, in Los Angeles, California, January 25, 2011. [Photo/Agencies]

The judge presiding over the case against Dr. Conrad Murray also set a trial date for March 28. Murray, who had his license to practice medicine suspended as a condition for his bail, faces up to four years in prison if convicted.

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Murray was with the pop singer when he died at age 50 at a rented Los Angeles home on June 25, 2009, from what coroners ruled was an overdose of the powerful anesthetic propofol and a cocktail of sedatives.

The doctor was ordered to stand trial earlier this month after a six-day preliminary hearing in which witnesses testified that Murray was slow to call for help on the morning of Jackson's death, and that he tried to hide evidence of propofol in the singer's bedroom.

Defense lawyers have suggested that the "Thriller" singer may have injected himself with the fatal dose of propofol, which he was using as sleep aid while rehearsing for a series of planned comeback concerts in London.

Involuntary manslaughter, to which Murray pleaded not guilty, is defined as unintentional killing without malice and is a lesser charge than murder.