Aurora shooting suspect James Holmes, who shot and killed 12 people in a theater in 2012, was found sane by two experts immediately following the attack, prosecutors say.
James Holmes, 27, has admitted the killings, but pleaded not guilty on grounds of insanity.
He opened fire during the midnight premiere of a Batman movie in Aurora, Colorado, in July 2012.
Officials say he was wearing body armor, threw smoke canisters and shot at people trying to escape.
If the jury finds him not guilty on grounds of insanity, James Holmes will spend the rest of his life in a mental institution for the criminally insane.
Otherwise James Holmes faces the death penalty.
During opening statements on April 27, District Attorney George Brauchler said both mental health evaluators agreed on James Holmes’ mental state at the time of the attack.
“Both of them said the same thing – that the guy was sane when he tried to murder all those people in the theatre,” he said.
Prosecutors have argued the attack was clearly premeditated, with James Holmes planning and amassing weapons for months, as well as elaborately booby-trapping his apartment to kill anyone who tried to enter.
His parents wrote a letter to the Denver Post in December calling for his life to the spared.
Robert and Arlene Holmes said their son was “not a monster”, but suffers from severe mental illness.
The trial comes after two and a half years of complicated legal questions related to the death penalty and the insanity plea, and after nearly three months of jury selection.
The mental health evaluations could be a key factor. Judge Carlos Samour ordered a second mental health exam after prosecutors said the first one was biased. Defense lawyers objected to a second test.
At the time of the shooting, James Holmes was a graduate student in neuroscience at the University of Colorado in Denver, but was withdrawing from his studies after failing a key exam.
When he was arrested, James Holmes’ hair had been dyed red in an apparent reference to the Joker, a Batman villain.
James Holmes appeared dazed in his first court appearance, and cameras were banned from further hearings.