CENTENNIAL, Colo. -- James Holmes, his hair dyed bright reddish-orange, appeared in court Monday in connection with the movie theater massacre he allegedly carried out last week, and a judge set July 30 for the filing of formal charges against him.

Wearing a maroon prison jumpsuit, Holmes, 24, stared blankly ahead for the most part, sometimes looking down or closing his eyes, as he sat silently beside an attorney. He appeared unshaven and expressionless during the appearance.

The judge told Holmes there was "probable cause to believe you committed the offense of first-degree murder" and said he would continue to be held without bond.

Judge William B. Sylvester also advised Holmes of his rights and ordered him to have no contact with victims of the July 20 theater shooting in Aurora, Colo., that left 12 people dead and 58 injured.

Holmes has not yet been charged officially, and Monday's appearance, called an advisement, precedes a more formal arraignment at the Arapahoe County Justice Center. The main purpose of the hearing was to show the court that there is sufficient reason to continue holding Holmes without bail.

Sylvester agreed to hold another hearing in a week, at which prosecutors will formally file charges.

Holmes is refusing to cooperate with investigators trying to learn what motivated the attack, police said.

"He's not talking to us," Aurora Police Chief Dan Oates told reporters.

He said Holmes had clammed up since his arrest early Friday after he allegedly opened fire on moviegoers at a midnight premiere of the new Batman film, "The Dark Knight Rises," in Aurora, a Denver suburb.

In San Diego, an attorney for Holmes' family, Lisa Damiani, could not shed any light on the defendant's motives or frame of mind. "The family has elected not to discuss James or their relationship with James at this time," she told reporters. Nor would the parents, Robert and Arlene Holmes, talk about their son's physical appearance or demeanor in court, Damiani said.

She acknowledged that "everyone's concerned" about the prospect of the death penalty, which she said is "highly likely" in the case, given that Colorado is a "death-penalty state."

Arapahoe County District Attorney Carol Chambers told reporters after the hearing that a decision on whether to pursue the death penalty in the case will be made with input from victims and their families.

Chambers said she had no information about whether Holmes was on medication during his initial appearance and that she could not explain his lack of emotion and apparently dazed look as the hearing unfolded.

The former neuroscience student at the University of Colorado has been held since Friday in solitary confinement under tight security at the Arapahoe County jail in Centennial, about 15 miles south of Denver.

NYPD Commissioner Ray Kelly, a longtime associate of Aurora Police Chief Oates, said Friday that Holmes had dyed his hair red to look like the Joker, the Batman villain, and told police when arrested that he was the Joker. Oates would not confirm Kelly's account.

Witnesses did not describe the gunman as looking like the Joker -- who, as Batman fans know, actually has green hair -- or saying anything to indicate that he was adopting the persona of the fictional villain.

However, in 2008's "The Dark Knight," the second film of a Batman series called the Dark Knight trilogy, the Joker, played by the late actor Heath Ledger, wore a nurse's uniform and a red wig in one scene as he destroyed a hospital.

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