In 2012, James Holmes opened fire in an Aurora, Colorado movie theater, killing 12 people. But does he deserve to die?

Almost three years after James Holmes filled a Colorado movie theater with tear gas and bullets during a midnight screening of The Dark Knight Rises, killing 12 and injuring 70, his trial finally began on Monday afternoon. While the defense painted a portrait of a mentally ill boy in need of treatment, and the prosecution insisted he was a broken-hearted killer out for existential revenge, both sides unveiled similar narratives of a young life spun dangerously out of control.

Of course, each side came to rather different conclusions about whether Holmes understood the moral implications of attacking a roomful of strangers.

“The defendant does not have to prove that he was insane at the commission of the act,” Judge Carlos A. Samour Jr. told a jury made up of five men and 19 women—12 of them alternates—before opening statements began. “Rather, prosecution has the burden to prove beyond a reasonable doubt that the defendant was not insane at the time of the commission of the act.”

Jurors will decide if Holmes receives the death penalty, life in prison, or is confined to a mental health facility.

Whether or not District Attorney George Brauchler proves Holmes was sane that night, he certainly succeeded on Monday in capturing the horror and devastation of Colorado’s worst mass murder since Columbine. Dressed in a sharply tailored suit while navigating a powerpoint presentation, he took the jury through a powerful recreation of the 2012 shooting, playing the bullet-speckled audio of the 9-1-1 call and describing the details of the victims’ wounds while pointing at Holmes, whose wrists and ankle were tethered discretely to the floor by a cable.

“Through this door is horror,” Brauchler said between long, dramatic pauses. “Through this door is bullets, blood, brains, and bodies. Through this door, one guy, who felt as if he had lost his career, lost his love life, lost his purpose, came to execute a plan in his heart and mind for two and a half months.”

During a two-hour monologue about Holmes, the “wicked smart” neuroscience student who was dumped by the first person who had sex with him, quit school, and went on a rampage, Brauchler punctuated the story every ten minutes or so with a short biography of one of the victims, displaying their photo on a nearby TV. Rebecca Wingo, mother of two, planned to be a social worker. Caleb Medley was an aspiring stand-up comic.

The detailed account of Holmes’s plot was nothing if not impressive. Brauchler described the elaborate yet ultimately failed booby-trap bomb in his apartment, the four weapons and hundreds of rounds of ammunition he’d prepared, the armor covering “every millimeter of his body.” He argued that Holmes strategically selected the theater for its minimal amount of exits—and that while making these plans, the accused wrote emails to his parents and flirted with girls on dating sites, seemingly a mentally acute person.

Following his own opening statement, public defender Daniel King expressed suspicion at Brauchler’s motives in focusing on the victims and the way they died.

“I’m concerned that the prosecutor representing the government, your government, just stood before you and talked about the ‘horrors’ of what took place in the movie theater, and I saw the impact on your faces,” King said. “Nothing he said is contested by the defense. Mr. Holmes has entered a plea of not guilty by reason of insanity, essentially admitting that he was the person in the theater, pulling the trigger.”

According to Aya Gruber, a criminal law professor at the University of Colorado, Boulder, “insanity” is strictly a legal term, not a medical one, and in order to be declared legally insane, you must have been not only been diagnosed with a mental illness, but demonstrate that it was that illness that prevented you from understanding right from wrong when committing a crime.

If that can be demonstrated, then “technically they’re supposed to acquit him,” Gruber explains. “But in my experience, juries really dislike acquitting people who do monstrous things on the basis of insanity. Instead, they look for whether he could plan, was rational and in control of his senses, and then they can find him to be sane.”

Technically, Gruber points out, the jury is not supposed to do that, but prosecutors know better.

“So you’ll notice in Brauchler’s opening statement he said that the guy scouted out the movie theater and meticulously planned the crime,” she says. “That shouldn’t matter that much. If we believed all of this planning was pursuant to a delusion, we should acquit him. But juries are highly reluctant to acquit people who seemed in control of their actions… There’s a way to try the case where they’re kind of encouraging the jury not to follow the law.”

Brauchler said that two doctors who had examined Holmes by order of the court following the shooting had concluded that he was sane, while King argued that there were 20 doctors who had determined that Holmes suffered from some kind of schizophrenia.

Both sides agreed that there was something not right with Holmes for some time; Brauchler pointed out that in his journal Holmes wrote that since middle school he’d had “a long-standing hatred of mankind,” and that he’d “had the obsession to kill since he was a kid.” The defense and prosecution agree on the facts that he was once a gifted student whose abilities declined while pursuing his graduate degree at the University of Colorado Anschutz Medical Campus. This, followed by his first girlfriend rejecting him, was apparently the germination of his turn toward violence.

“He tried to murder a theater full of people to make himself feel better, because he thought it would increase his self-worth,” Brauchler argued. Of course, Holmes’s defense team looks at the same narrative and sees a textbook pattern of schizophrenic symptoms.

“James Holmes was genetically gifted with a high IQ, and genetically cursed with a family history of pervasive and serious mental illness,” defense lawyer Katherine Spengler said. “And those things don’t cancel each other out, they coexist.”

The defense pointed toward his journal, which suggested that Holmes had “fought for years and years to overcome [his] biology,” and argued that his pursuit of neuroscience was an attempt to better understand and one day repair his ailing brain. “Schizophrenia lies latent in people, there are signs of it as a child, but it blossoms into full psychosis when individuals are in their early twenties,” King added.

“He had homicidal thoughts as a child,” Spengler said. “He had thoughts about nuclear winters, which were coping mechanisms to stress.”

Defense attorneys suggested Holmes’s illness was apparent as a child, went underground, and then resurfaced at the age of 24—the tail end of period when schizophrenia often surfaces in men. His mental health issues were said to continue throughout his stay in prison, where King said Holmes would cover himself in his own feces, eat paper, lick the walls, and declare himself to be Peter Pan.

Like the prosecutor, Spengler said that Holmes’s motive for the massacre was that “by killing others, he could gain value and acquire worth. He believed that by killing others would fundamentally change his life.” But while Brauchler sees this as mere vanity taken to a violent extreme, Spengler argues that it is evidence of “delusional thinking.”

Gruber, the law professor, says that it’s pretty routine for both sides of an insanity defense trial to follow a similar storyline in their arguments while coming to completely different conclusions. She says this is due to the legal ambiguity over what constitutes a sane bad person and a sick person who couldn’t help themselves.

“It’s a delicate fiction that people who commit heinous crimes are somehow completely mentally fit, and just evil,” she says. “Criminal law hinges on the idea that some people are responsible for their deranged acts, and other people aren’t—and where do you find that fine line between someone who is a sociopath and immoral and should go to jail, and a sociopath who is ill and should go to a mental institution? It’s a such a fine line that the narrative can support either side of that line.”

Given the reluctance most juries have for accepting insanity pleas, along with the extreme political waves this crime has caused (controversial gun legislation, for instance), the defense has their work cut out for them in trying to convince a Colorado jury that James Holmes was not directly responsible for all those traveling bullets.

Still, on the first day of a trial that is expected to last until Labor Day, King attempted to guide the jury away from the hysteria of public outcry and first-glance assumptions, and remind them what is expected of them as jurors.

“As I stand before you I feel a great wave of pain and emotion from this community, and from these victims. What I’m going to suggest to you through the course of this trial, is that if the flood waters rise, the only thing to do is to move above the water-line together—there is the fortress of the law. There is no room in the fortress of the law for hatred. There is no room for retribution, or vengeance. The law commands that you fairly and rationally consider all the evidence in the case, and you decide whether the prosecution has proven beyond all reasonable doubt that Mr. Holmes was not insane when he stepped into that movie theater. Not whether mass murder is wrong, not about how badly the victims were harmed, not about gun control, or mental health treatment. Not here in the fortress of the law.”