LOS ANGELES -- A judge denied a request Monday by lawyers for the doctor convicted of causing Michael Jackson's 2009 death to have an independent laboratory test the contents of a key vial of evidence.

Days before the Nov. 29 sentencing of Dr. Conrad Murray, Superior Court Judge Michael Pastor said defense attorneys could have sought the testing months ago or during the doctor's six-week trial but chose not to. "You're not involved in fishing, you're involved in foraging," he said.

Murray's attorneys wanted a lab to test a small amount of liquid found in a vial of the anesthetic propofol authorities contend was used to help Jackson sleep the day he died.

Defense lawyer J. Michael Flanagan argued the results would reveal the accuracy of a theory by a prosecution expert who testified Murray left Jackson's side while the singer was on an IV drip of propofol and the painkiller lidocaine.

Murray had been giving Jackson nightly doses of propofol to help the singer sleep as he prepared for a series of comeback concerts.

Deputy District Attorney David Walgren contended there was no legal basis for the testing and said Murray received a fair trial. Pastor examined the propofol vial, which was found in the closet of Jackson's bedroom, before issuing his ruling.

Flanagan said it didn't occur to him that the contents of the vial should be tested until after the conclusion of Murray's trial, which ended Nov. 7 with the conviction of the cardiologist on an involuntary manslaughter charge.

Flanagan said if prosecution expert Dr. Steven Shafer's theory is correct, the small amount of liquid that remained in the vial should contain lidocaine. In that case, "that's the ballgame" and would prove Murray did leave the singer alone on an IV drip, Flanagan said.