(Adds comment from man wounded in shooting and other details)
By Keith Coffman
CENTENNIAL, Colo., March 12 (Reuters) - A Colorado judge presiding over the case of accused theater gunman James Holmes entered a not guilty plea on his behalf on Tuesday to charges he went on a shooting spree in a Denver suburb nearly eight months ago and killed 12 moviegoers.
Arapahoe County District Judge William Sylvester made the move after declining a defense request for a continuance, paving the way for a trial to begin in August. Holmes' lawyers said they were not ready to enter a plea.
Holmes faces multiple counts of first-degree murder and attempted murder stemming from the July 20 rampage that also wounded 58 people and was one of the deadliest mass shootings in U.S. history.
"This matter has been pending since July 2012," Sylvester said. "I acquiesced to the defense and put off the date as long as we could."
Holmes, who has grown shaggy hair and a beard since his arrest, glanced briefly at his parents as he entered the courtroom on Tuesday.
His lawyers are expected to mount an insanity defense for Holmes, 25, who surrendered to officers outside the theater in the Denver suburb of Aurora within minutes of the mass killing.
Prosecutors have depicted the former neuroscience graduate student at the University of Colorado at Denver as a young man whose once promising academic career was in tatters.
He failed graduate school oral board exams in June and one of his professors suggested he may not have been a good fit for his competitive doctoral program, prosecutors said.
Arapahoe County District Attorney George Brauchler said in court on Tuesday that his office would announce at some point during court hearings in the first week of April whether it will seek the death penalty for Holmes.
Sylvester said that, even though he was entering a simple not guilty plea on behalf of Holmes, the defense could later substitute a plea of not guilty by reason of insanity. Sylvester also scheduled a four-week trial for Holmes to begin on Aug. 5.
Marcus Weaver, who was wounded in the theater shooting, attended the court hearing and said afterward he was worried about a drawn-out legal proceeding if Holmes' defense team mounts an insanity defense.
"If he carries this out all the way, we should seek the death penalty," Weaver said outside the courtroom.
Weaver said he personally would be satisfied with Holmes receiving life without the possibility of parole if the defendant pleads guilty to the charges.
The automatic plea by judge Sylvester came a day after he ruled that Holmes could be medicated for psychiatric interviews and possibly face a polygraph test if he chooses to raise an insanity defense.
Holmes' lawyers have argued he should not be drugged while undergoing examinations by court-appointed psychiatrists.
During the hearing on Tuesday, Holmes' attorney Daniel King said the defense was still not ready for a plea because it was evaluating the ruling on psychiatric evaluations. King sought to postpone the entering of a plea until at least May 1.
"If we enter a plea, the court will order a state evaluation and our evaluation would be truncated and cut short," King said.
Among those in attendance in court on Tuesday were people who suffered wounds or lost family in the July theater shooting. When Holmes' defense team asked to postpone the arraignment, some of those in attendance gave audible sighs in reaction.
Holmes' lawyers unsuccessfully sought earlier this month to have the state's insanity-defense law declared unconstitutional by arguing it requires defendants to incriminate themselves to court-appointed psychiatrists.
Defense attorneys also revealed in pleadings released last week that Holmes spent several days in a psychiatric unit in November, frequently in restraints, because jail officials believed he was a danger to himself.
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.
Holmes had booby-trapped his apartment near the theater with explosives, which police said was intended to draw authorities away from the movie house while he was carrying out his assault. The bombs were later defused safely. (Additional reporting by Jann Tracey, Writing by Alex Dobuzinskis; Editing by Cynthia Johnston Ellen Wulfhorst, Lisa Von Ahn, Jeffrey Benkoe and Andre Grenon)