Los Angeles, California (CNN) -- The judge in the involuntary manslaughter case against Dr. Conrad Murray on Wednesday approved a plan to allow defense lawyers to test residue from syringes and an intravenous drip found in pop star Michael Jackson's home after his June 25, 2009, death.
During the court hearing, one of Murray's attorneys, J. Michael Flanagan, alleged that coroner's officials should have done "quantitative" analysis of the items to help determine "the means of who injected Jackson" with the powerful drugs that killed him.
Murray told investigators he injected the singer with sufficient amounts of propofol and to help him sleep the night of his death, but denied administering concentrations found in Jackson's blood cited by investigators, which amounted to levels used in major surgery.
Deputy District Attorney David Walgren dismissed the defense attorney's claim, saying that his office has shared everything and never objected to testing the syringes or intravenous drip as long as the coroner followed proper procedures. "The theory that they're running with is Michael Jackson killed himself," said prosecutor Walgren in court.
Murray is charged with involuntary manslaughter in Jackson's death, which the Los Angeles County coroner ruled was from an overdose of propofol, a powerful anesthetic used to put surgical patients to sleep, in combination with benzodiazepine, a sedative used to relieve an array of physical and psychological maladies.
The coroner also concluded the evidence did not support the self-administration of propofol.
The devices on which Judge Pastor has allowed testing were used to administer propofol as well as lidocaine, a drug commonly used as a local anesthetic in minor surgery.
Pastor warned defense attorneys they would have to acknowledge the risk of a loss of evidence if the extremely small amount of residue is given to them for testing.The sample would need to be halved so prosecutors could have an equal quantity to test for a rebuttal.
His ruling requires Murray's lawyers to decide whether hire a private lab or allow the Los Angeles coroner to test the residue.
Outside the courtroom, Flanagan said he needed to consult with experts before deciding whether to test the items.
Walgren estimated it would take about eight days to present witnesses in court to prove there is probable cause to put Murray on trial.
The preliminary hearing for Murray is set to begin next Tuesday and is expected to last about two weeks. He remains free on $75,000 bond.