Dr. Conrad Murray is charged with involuntary manslaughter in pop singer Michael Jackson's June 2009 death.
The announcement from prosecutor David Walgren came during a Wednesday hearing in downtown Los Angeles during which the two sides clashed over who should test residue from two syringes found in Jackson's bedroom. Liquid in one of the syringes has already dried up and was now "salt," according to attorneys.
Defense attorneys want tests expedited on the syringes and an IV bag found in the singer's mansion after his death, saying they are rapidly deteriorating.
Attorney Michael Flanagan said a huge amount of the anesthetic propofol was found in Jackson's body but his client has said he gave him only 25 milligrams on the drug.
Walgren suggested that the defense will claim Jackson killed himself by injecting more of the drug into himself.
Quantities of substances in the syringes and IV bag could be crucial to explaining how the singer died, according to lawyers. The testing could determine the quantities of drugs in the items, which the cardiologist's lawyers say is crucial information for trial.
Murray has pleaded not guilty to involuntary manslaughter.
Authorities contend he administered a lethal dose of sedatives, including the anesthetic propofol, to Jackson in the bedroom of his rented mansion in June 2009.
Officials tested what was in the items and found traces of propofol and lidocaine, according to court documents.
But the amounts of the substances were not determined, and defense attorneys contend that may be significant in the case expected to hinge on technical and scientific data.
Defense attorney Ed Chernoff says substances in one broken syringe found at the mansion had dried up since June 2009, when the judge ordered the evidence preserved. The tests sought by Murray's attorneys will destroy the samples and can only be performed once.
Tissue samples in Jackson's body were tested for levels of various substances and led to the coroner's determination that the pop singer died in part from acute propofol intoxication.
The anesthetic is supposed to be administered in hospital settings, but Murray told investigators he had been providing it to Jackson as a sleep aide and had been trying to wean him off the drug.
Chernoff has said the doctor did not give Jackson anything that should have killed him.
The tests are likely to be conducted by the Los Angeles County coroner's office.
A preliminary hearing in the case against Murray is scheduled to begin Jan. 4.
Prosecutors will lay out some of their evidence during the hearing, and the judge will then decide whether there is enough evidence to order Murray to stand trial.