The former graduate student accused of opening fire at a midnight screening of the new “Batman” film in Colorado, killing 12 people, was charged on Monday.
He was charged with 24 counts of first-degree murder, making him eligible for the death penalty if convicted.
James Holmes, who was arrested behind a suburban Denver multiplex minutes after the July 20 shooting at a packed showing of “The Dark Knight Rises”, also faces 116 counts of attempted murder in one of the worst outbursts of U.S. gun violence in recent years.
Fifty-eight people were wounded in the attack, some of whom remain in critical condition.
Prosecutors have said a decision could be months away on whether to seek the death penalty against Holmes, 24, who made his second court appearance on Monday.
Colorado has three men on its death row and but has not executed a condemned inmate since 1997.
Arapahoe County District Attorney Carol Chambers’ office charged Holmes with two counts for each victim, one for carrying out the crime “after deliberation” and the second for “malice manifesting extreme indifference to human life”.
Holmes, who authorities say styled himself after Batman’s comic-book nemesis “The Joker”, appeared in court clad in jail garb, his hair still dyed bright orange but with the color fading to pink in places.
He sat impassively at a table with two defence 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 September 27, tentatively scheduling a preliminary hearing for the week of November 13.
Police say Holmes entered Theatre 9 at the Century 16 multiplex in the Denver suburb of Aurora wearing tactical body armour 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, six-year-old Veronica Moser-Sullivan, was the youngest of those who died in the shooting.
Moser’s aunt, MaryEllen Hansen, said after Monday’s hearing that she found Holmes a “diabolical, evil presence”.
“But he looked very sane to me. He really did. His reaction looked different,” she said.
“When we’ve saw him before, he looked like he was kind of spaced out or out of touch. But he seemed very, very alert today and very lucid as to what was going on.”
Prosecutors, who are under a protective or “gag” order imposed in the case by the judge, declined to explain their decision to file the double charges, but legal experts say it could to be a strategy to offer jurors more than one path to a guilty verdict.
During the hearing, defence attorney Tamara Brady asked that prosecutors turn over evidence collected in the case.
The defence is seeking a package that news reports have said was sent by Holmes to a University of Colorado psychiatrist, Lynne Fenton.
Prosecutors responded that they had not yet opened that parcel, which according to Fox News contained a notebook outlining his plans for the shooting, including stick-figure drawings.
Holmes, a San Diego native, was a doctoral student of neuroscience at the university’s Anschutz Medical Campus before turning in paperwork to drop out in June.
Court documents filed on Friday by defence lawyers said he had been a patient of Fenton, who is medical director for student mental health services on campus.
She is also listed as a member of the school’s behavioural threat-assessment team.
Neighbours and students in the North Aurora neighbourhood where Holmes lived said his withdrawal from the university would likely have triggered his eviction from his apartment because the building is reserved for people affiliated with the school.
Police have not offered a motive for the shooting rampage that stunned Aurora and evoked memories of the 1999 massacre at Columbine High School less than 32 km away in Littleton.
Authorities have said that following his arrest, Holmes called himself “The Joker” and experts say his mental state could play an important role in the case.
Police said Holmes was armed on the night of the shooting with a Smith & Wesson M&P .223 semi-automatic rifle, similar to an AR-15 assault rifle; a 12-gauge shotgun and a Glock .40-caliber handgun, according to police.
An additional Glock .40-caliber handgun was found in his car, and all the weapons had been bought legally in the previous 60 days.