Lawyers for the doctor charged with involuntary manslaughter in the death of Michael Jackson could claim the pop star killed himself when a hearing begins next week, a prosecutor said on Wednesday.

In a court session to discuss evidence in the case against Dr. Conrad Murray, Los Angeles Deputy District Attorney David Walgren said he believes it is clear defense attorneys are looking into that theory, which has long been a consideration.

Outside the courtroom, Murray's attorney J. Michael Flanagan declined to comment on Walgren's statement.

"I'm not going to respond to that characterization. But apparently it is a consideration of Mr. Walgren," Flanagan told reporters.

Walgren spoke at a hearing in which a judge cleared the way for Murray's defense to test residue from syringes and an IV tube used to administer drugs to Jackson.

The "Thriller" singer died at age 50 on June 25, 2009, of an overdose of prescription drugs, primarily the powerful anesthetic propofol which can be used in surgery. Other drugs in Jackson's system included lorazepam, known under the brand names Ativan and Temesta, and diazepam, the generic version of Valium.

Murray, hired as Jackson's physician while the singer prepared for a series of concerts that would have begun in July 2009, has admitted giving Jackson propofol to help him sleep. But Murray has pleaded not guilty to the charge of involuntary manslaughter.

The court session on the syringe testing came only days before a January 4 start date for a preliminary hearing in which a judge will decide if there is enough evidence against Murray to proceed to a full trial.

Representatives for the prosecution and defense told Reuters they expect the preliminary hearing to begin as planned and take roughly two weeks to complete.