In a packed Denver-area courtroom Monday, Holmes, 24, sat silently and did not react as he heard formal charges against him, including first-degree murder for each of the 12 who died and attempted murder for each of the 58 people who were injured in one of the deadliest mass shootings in recent U.S. history.
At one point, a shackled Holmes, still with his hair dyed orange-red, leaned over to speak with one of his lawyers and furrowed his brow.
When the judge asked the former neuroscience student if he agreed with his attorney's request to delay a future court hearing so his defense team could have more time to prepare, Holmes said softly: "Yea."
Some of the people in the court wore Batman T-shirts. Several people clasped their hands and bowed their heads as if in prayer before the hearing. At least one victim attended, and she was in a wheelchair and had bandages on her leg and arm. One unidentified man glared at Holmes throughout the hearing.
Holmes was charged with 24 counts of murder, two each for the 12 victims, and 116 counts of attempted murder, two each for the 58 injured.
For the murder charges, one count included murder with deliberation, the other murder with extreme indifference. Both counts carry a maximum death penalty upon conviction; the minimum is life without parole.
A conviction under extreme indifference means that any life sentences would have to be served consecutively, not concurrently, said Craig Silverman, a former chief deputy district attorney in Denver.
In addition, Holmes was charged with one count of possession of explosives and one count of a crime of violence. Authorities said booby trapped his apartment with the intent to kill any officers responding there the night of the attack.
Legal analysts expect the case to be dominated by arguments over the defendant's sanity.
Attorneys also argued over a defense motion to find out who leaked information to the news media about a package the 24-year-old Holmes allegedly sent to his psychiatrist at the University of Colorado Denver.
Authorities seized the package July 23, three days after the shooting, after finding it in the mailroom of the medical campus where Holmes studied.
Several media outlets reported that it contained a notebook with descriptions of an attack, but Arapahoe County District Attorney Carol Chambers said in court papers that the parcel hadn't been opened by the time the "inaccurate" news reports appeared.
Prosecutor Tamara Brady said Monday she will subpoena psychiatrist Lynne Fenton to testify in the dispute over whether a notebook is privileged because of a possible doctor-patient relationship. A hearing on the matter was set for Aug. 16.
District Chief Judge William Sylvester set an Aug. 9 hearing on a motion filed by news organizations seeking to have the case docket unsealed.
A hearing to update the status of the case was set for Sept. 27. A hearing to review evidence matters and to determine whether Holmes should continue to be held without bail was set for the week of Nov. 9.
Unlike Holmes' first court appearance July 23, Monday's hearing was not televised. At the request of the defense, Sylvester barred video and still cameras from the hearing, saying expanded coverage could interfere with Holmes' right to a fair trial.
Last week, Sylvester allowed a live video feed that permitted the world its first glimpse of the shooting suspect. With an unruly mop of orange hair, Holmes appeared bleary-eyed and distracted. He did not speak.
Security was tight for Monday's hearing. Armed officers were stationed on the roof of both buildings at the court complex, and law enforcement vehicles blocked entrances to the buildings.
Investigators said Holmes began stockpiling gear for his assault four months ago and bought his weapons in May and June, well before the shooting spree just after midnight during a showing of "The Dark Knight Rises." He was arrested by police outside the theater.
Analysts said that means it's likely there's only one main point of legal dispute between prosecutors and the defense.
"I don't think it's too hard to predict the path of this proceeding," Silverman said. "This is not a whodunit. ... The only possible defense is insanity."
Under Colorado law, defendants are not legally liable for their acts if their minds are so "diseased" that they cannot distinguish between right and wrong. However, the law warns that "care should be taken not to confuse such mental disease or defect with moral obliquity, mental depravity, or passion growing out of anger, revenge, hatred, or other motives, and kindred evil conditions."
Experts said there are two levels of insanity defenses.
Holmes' public defenders could argue he is not mentally competent to stand trial, which is the argument by lawyers for Jared Loughner, who is accused of killing six people in 2011 in Tucson, Ariz., and wounding several others, including Rep. Gabrielle Giffords. Loughner, who has pleaded not guilty to 49 charges, has been diagnosed with schizophrenia and is undergoing treatment at a Missouri prison facility in a bid to make him mentally fit to stand trial.
If Holmes' attorneys cannot convince the court that he is mentally incompetent, and he is convicted, they can try to stave off a possible death penalty by arguing he is mentally ill. Prosecutors will decide whether to seek the death penalty in the coming weeks.
He ultimately could verbally enter a plea to the anticipated dozen first-degree murder charges, or his attorneys could enter it for him.
Sam Kamin, a law professor at the University of Denver, said there is "pronounced" evidence that the attack was premeditated, which would seem to make an insanity defense difficult. "But," he said, "the things that we don't know are what this case is going to hinge on, and that's his mental state."
Friends in Southern California, where Holmes grew up, describe him as a smart, sometimes awkward youth fascinated by science. He came to Colorado's competitive neuroscience doctoral program in June 2011. A year later, he dropped out shortly after taking his year-end exam.
Sylvester has tried to tightly control the flow of information about Holmes, placing a gag order on lawyers and law enforcement, sealing the court file and barring the university from releasing public records relating to Holmes' year there.
A consortium of media organizations, including The Associated Press, is challenging Sylvester's sealing of the court file.
On Friday, court papers revealed that Holmes was seeing a psychiatrist at the university. But they did not say how long he was seeing Fenton and if it was for a mental illness or another problem.
The University of Colorado's website identified Fenton as the medical director of the school's Student Mental Health Services.
An online resume listed schizophrenia as one of her research interests and stated that she sees 10 to 15 graduate students a week for medication and psychotherapy, as well as five to 10 patients in her general practice as a psychiatrist.
Online: Complaint against Holmes