(Adds comments from lead defense lawyer, paragraphs 16-20)
By Keith Coffman
CENTENNIAL, Colo., July 14 (Reuters) - A prosecutor broke down on Tuesday as he said the man in black who gunned down a dozen people in a Colorado movie theater had nothing but "mass murder" on his mind when he went on the rampage three years ago.
District Attorney George Brauchler said 400 people went to a midnight premiere of a Batman film in the Denver suburb of Aurora, happy and hopeful of being entertained by a tale of a black-clad hero fighting for justice.
"But that's not what happened," Brauchler said. "Instead, a different figure appeared by the screen dressed all in black, and he came there with one thing in his heart and in his mind, and that was mass murder."
His remarks came during closing arguments in the almost three-month-long capital trial of James Holmes, as jurors prepare to decide if he was legally insane or a calculating mass murderer when he staged his attack.
It was the last time attorneys address the jury before the panel begins deliberating the fate of the 27-year-old California native on Wednesday.
Holmes, who has pleaded not guilty by reason of insanity, faces 165 counts of murder, attempted murder and explosive charges stemming from the July 20, 2012 rampage.
When the shooting stopped, 12 moviegoers lay dead and 70 were either wounded by gunfire or injured fleeing the theater. Prosecutors will seek the death penalty for Holmes if he is convicted.
Pointing at Holmes and calling him "this guy," Brauchler said he packed "overwhelming firepower," including a semi-automatic rifle and steel-penetrating rounds, and that he used tear gas to create a "kill box" in the theater.
At one point, as the prosecutor showed photos of victims on a courtroom television, his voice broke.
"Forgive me," Brauchler said, removing his glasses and wiping his eyes. "I thought I could do this without ... Oh man."
There was another emotional moment when the prosecutor showed a photo of Holmes' youngest victim, 6-year-old Veronica Moser-Sullivan, while playing audio from a 911 call with gunfire in the background.
"That guy was sane beyond reasonable doubt. He needs to be held accountable for what he did," Brauchler said.
The prosecution called more than 200 witnesses during the trial, interspersing testimony from wounded survivors with others who detailed his purchases of weapons, body armor, and the bomb-making materials he used to booby-trap his apartment.
They also called two court-appointed psychiatrists who testified that while severely mentally ill, the onetime neuroscience graduate student was sane when he plotted and carried out the massacre.
The defense case centered on two hired psychiatrists who both concluded Holmes is delusional and schizophrenic, that he heard voices commanding him to kill to enhance his "self worth," and cannot be held legally accountable.
"When Mr. Holmes stepped into that theater ... he had lost touch with reality. He had been consumed by a psychotic process," lead defense lawyer Daniel King told jurors in his closing argument.
"He was suffering from a mental disease that he'd had for more than 10 years. ... The evidence is clear: that he could not control his thoughts, that he could not control his actions, and he could not control his perceptions."
King asked why Holmes told a psychiatrist at the University of Colorado weeks before the rampage that he had thoughts of killing a lot of people.
"Mr. Brauchler wants to talk about it as if there's nothing wrong with him, and he is just logically pursuing things. But where's the logic?" King said, pointing at the prosecutor.
"It defies logic. That's the psychotic process, and that's what this guy is asking you to pretend doesn't exist."
Holmes has sat impassively throughout most of his trial. He has rarely interacted with his lawyers or acknowledged his parents, who have been in court most of the time.
So many victims and their relatives wanted to attend the closing arguments, prosecutors had to cycle them in and out of the packed, windowless courtroom in groups. (Reporting by Keith Coffman; Editing by Daniel Wallis and Tom Brown)