CENTENNIAL, Colo. (Reuters) - A Colorado judge on Monday opened the door to accused movie theater gunman James Holmes pleading not guilty by reason of insanity to charges he murdered 12 filmgoers last year, in a case that could bring the death penalty if he is convicted.
Arapahoe County District Judge Carlos Samour Jr. said he will give prosecutors and defense lawyers a chance to present further written arguments over ground rules for an insanity plea before allowing Holmes' lawyers to enter it, if they so choose, at his next court date on May 31.
Holmes, 25, faces multiple counts of first-degree murder and attempted murder in connection with the July 2012 shooting spree in a suburban Denver multiplex during a midnight screening of the Batman film "The Dark Knight Rises".
The Colorado theater attack ranks as one of the nation's deadliest shootings. Along with a rampage in December at Sandy Hook Elementary School in Newtown, Connecticut, it helped reignite a national debate on gun control.
A standard not-guilty plea, without the insanity defense, was entered on Holmes' behalf at a previous hearing in March, when his lawyers sought more time to shape their legal strategy.
In addition to the 12 members of the film audience slain in the theater shooting, 58 others were wounded by gunfire and another 12 suffered various other injuries in the ensuing pandemonium.
Should Holmes mount an insanity defense, prosecutors would bear the burden under Colorado law of proving he was mentally capable of knowing right from wrong at the time of the alleged crime in order to win a conviction.
But juries have typically shown reluctance to accept an insanity defense, legal experts said. Moreover, criminal defendants who plead insanity are potentially vulnerable under state law to self incrimination because they are required to cooperate with court-ordered psychiatric evaluations.
At the arraignment in March, defense lawyers said they were not ready to formally pursue an insanity defense.
"We now have a diagnosis that's complete," public defender Daniel King told the judge on Monday.
Samour said he took defense arguments at face value and did not believe Holmes' lawyers were engaging in "dilatory tactics."
"Good cause has been established" to permit a change in plea to not guilty plea by reason of insanity, he said.
INSANITY PLEA COULD COME BY END OF MONTH
The judge said he would rule by May 28 on the precise legal ramifications of an insanity plea, and set a hearing for May 31, in which Holmes would be advised of the consequences and could go through with a plea change at that time.
Holmes, sporting a shaggy beard and dressed in maroon prison garb, sat impassively as usual at the defense table without saying a word for the hour-long proceedings.
Prosecutors announced last month that they would seek to put the California native to death if he is convicted of the massacre, citing the "especially heinous, cruel or depraved" nature of the crime. Since it is a capital case, Samour is widely expected to grant a change of plea if one were sought.
Holmes' lawyers have said that their client suffers from an unspecified mental illness.
In court pleadings, they have cited two occasions on which Holmes has been hospitalized since his arrest - once for treatment of apparently self-inflicted head injuries and again when he was deemed a potential threat to himself and was admitted for several days to a psychiatric unit.
Prosecutors have depicted Holmes as a once-promising neuroscience doctoral candidate at the University of Colorado whose academic career fell into disarray. He had failed graduate school oral board exams in June 2012, and a professor suggested he may not have been a good fit for his program.
A university psychiatrist, Dr. Lynne Fenton, has testified that she treated Holmes more than a month before the shooting and that her professional relationship with him ended in mid-June of that year.
Police affidavits in the case said Fenton had advised campus authorities in June that Holmes had been having homicidal thoughts and that she had stopped seeing him after he began threatening her with text messages.
Police said a search of Holmes' apartment turned up a bottle of the anti-seizure medication clonazepam, which can also be used to treat anxiety disorders, and a bottle of the anti-depressant sertraline, known by its brand name Zoloft.
It is unclear if Holmes had either drug in his system when he was arrested.
Craig Silverman, a former Denver prosecutor now in private practice as a trial attorney, has said compelling evidence was offered during Holmes' preliminary hearing in January indicating Holmes was responsible for his actions.
As an example, he cited a posting found on Holmes' online dating profile from weeks before the shooting that carried the headline: "Will you visit me in prison?"
Prosecutors also presented considerable evidence suggesting that the movie theater rampage was planned out well in advance.
On the night of the shooting, Holmes is accused of entering the theater with a ticket he bought 12 days earlier, then leaving through a rear exit minutes into the movie and re-entering moments later wearing body armor and a gas mask.
Armed with a shotgun, pistol and semi-automatic rifle, authorities say, Holmes lobbed a tear gas canister into the auditorium and sprayed moviegoers with bullets until one of his guns jammed, then surrendered to police without a struggle in the parking lot behind the theater.
Police testified that Holmes began assembling his collection of guns and ammunition two months before the shooting and scouted out the multiplex weeks ahead of time. His apartment near the theater was also found to have been booby-trapped with explosives. The bombs were later defused.
Holmes' trial is scheduled for February 2014.
(Writing by Steve Gorman; Editing by Cynthia Johnston, Bernard Orr and David Gregorio)