He sat impassively at a table with two defense lawyers through the 45-minute hearing but seemed more alert than during his initial court appearance a week ago, when he looked dazed and groggy.
The former neuroscience student spoke only once, quietly answering, "Yes," in response to a question from Arapahoe County District Judge William Sylvester. He mostly kept his gaze lowered and did not look at a courtroom gallery packed with members of the media and victims' family members.
The judge set a pre-trial hearing for Sept. 27, tentatively scheduling a preliminary hearing for the week of Nov. 13.
Police say Holmes entered Theater 9 at the Century 16 multiplex in the Denver suburb of Aurora wearing tactical body armor and a gas mask and tossed smoke bombs before spraying moviegoers with bullets from three guns.
Authorities who rushed to his apartment following the movie house massacre said they found it wired with enough explosives to bring down the three-story building, and spent several days dismantling the booby traps. Holmes was also charged on Monday with possessing an explosive device.
Pregnant survivor Ashley Moser suffered a miscarriage following the shooting, but the loss of her fetus did not alter the number of murder charges because the unborn cannot be counted as homicide victims under Colorado law.
Moser, 25, was left paralyzed from the waist down from her own bullet wounds. Her daughter, 6-year-old Veronica Moser-Sullivan, was the youngest of those who died in the shooting.