District Judge Carlos Samour, Arapahoe County prosecutors and lawyers for Holmes discussed jury selection, which is scheduled for October, during a hearing in Centennial, Colo. Samour delayed ruling on motions to close jury selection to the public and news media, and to ask jurors about their attitudes to an insanity defense.
Holmes is charged with killing 12 people and wounding many more when he opened fire during a midnight showing of The Dark Knight Rises in 2012 at a theater in Aurora, Colo. If he is convicted, the same jury will decide if he should be sentenced to death.
Both sides want jury selection closed, while news organizations have objected. The lawyers say the pool could be tainted by coverage of the details of selection during what is expected to be a long process.
The prosecution objects to asking jurors about the insanity defense. Holmes has entered a plea of not guilty by reason of insanity.
Holmes, who was shackled, remained quiet during the two-hour hearing.
With Holmes facing more than 160 separate counts, including 12 of murder and many more of attempted murder, the trial is expected to take months.
"It's not like we do this type of case every day," Samour said Thursday. "I think it's a first for all of us."
Holmes had dropped out of a graduate neuroscience program at the University of Colorado in Aurora a few weeks before the mass shooting.
Last year, prosecutors rejected an agreement that would have allowed Holmes to plead guilty without facing the death penalty.
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