Colorado's long-awaited cinema massacre trial began this evening with jurors asked to decide whether gunman James Holmes was insane when he killed a dozen movie goers in 2012, or a calculating mass murderer who deserves execution.
Public defenders trying to spare the life of the one-time neuroscience graduate student, and prosecutors seeking the death penalty, started presenting their opening statements in a courtroom on the outskirts of Denver.
Mr Holmes, 27, pleaded not guilty by reason of insanity to killing 12 people and wounding 70 inside a crowded midnight screening of the Batman film "The Dark Knight Rises."
He was armed with a handgun, shotgun and semi-automatic rifle.
Arapahoe County District Attorney George Brauchler began by painting a picture for jurors - 19 women and five men - of the cool night in July when 400 people filed into a cinema in suburban Aurora to be entertained.
"One person came there to slaughter them ... 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 for his life, but for two-and-a-half months in his mind," Mr Brauchler said.
"He tried to murder a theatre full of people to make himself feel better, and because he thought it would increase his self-worth," he said, pointing at the defendant.
Mr Holmes, wearing glasses, a white shirt and stubble, looked on impassively as Mr Brauchler played recordings of frantic, gunfire-filled 911 calls from that night.
Mr Brauchler said two court-appointed forensic psychiatrists had studied Mr Holmes and concluded he was sane when he carried out the shooting.
"This guy has a superior intellect ... he is smart," Mr Brauchler said.
He said Mr Holmes planned to escape after the shooting, including by using devices thrown to puncture the tires of any police cars that might chase him, but realised he was outnumbered by officers and decided to give up.
Arapahoe County District Court Judge Carlos Samour has said he expects the trial to take four or five months.
Lawyers for Mr Holmes, who is charged with multiple counts of first-degree murder and attempted murder, concede he was the lone gunman but have said the Southern California native was in the throes of a psychotic episode when he plotted and carried out the attack.
Police say Mr Holmes, dressed in a gas mask, helmet and body armour, lobbed a teargas canister into the screening at Aurora's Century 16 multiplex, then opened fire.
Mr Brauchler said on Monday Mr Holmes had also been listening to techno music on headphones at the time.
The defendant appeared in court days after the rampage looking disoriented, and with his hair dyed orange.
Mr Holmes, who graduated with honours from the University of California, Riverside, has no criminal record.
He had been courted by neuroscience doctoral programs, but withdrew from a graduate program at the University of Colorado's Anschutz Medical Campus before the attack.
Mr Holmes' public defenders will focus throughout the trial on his mental state, said long-time Colorado criminal defence lawyer Mark Johnson.
"The defence theme from the get-go will be that as a civilized society, we don't put mentally ill people to death," Mr Johnson said.
Mr Holmes has been hospitalised at least twice since his arrest, according to his lawyers. Once he was treated for an apparent self-inflicted head injury.
Another time he was taken to a Denver psychiatric ward where his lawyers said he was held "frequently in restraints" for several days.
Colorado prosecutors rarely seek the death penalty, and the state has just three inmates on death row.
