A slide of Dr. Conrad Murray and propofol is projected during the prosecution's opening arguments in Murray's involuntary manslaughter trial in downtown Los Angeles on Sept. 27, 2011.

An appellate court denied a request Monday that it order forensic testing on a piece of evidence that Dr. Conrad Murray’s lawyers claimed might cast doubt on his guilt in Michael Jackson’s death.

The 2nd District Court of Appeal issued the decision without comment. Attorneys for Murray, who is serving a two-year manslaughter sentence, had asked for lab testing on residue from a propofol vial found in the pop star’s room.

The doctor’s fingerprint was on the vial, and prosecutors theorized that it held the dose of the surgical anesthetic propofol that killed Jackson on June 25, 2009. Murray’s defense, which maintained that Jackson administered the fatal dose himself, asked late in the trial for testing, but was rebuffed by the trial judge who said the request was not timely.

An attorney for Murray, Valerie Wass, said she planned to petition the state Supreme Court to order testing on the drug bottle.