They had been weighing whether the defense’s presentation of Mr. Holmes’s mental illness, his lack of criminal record before the shooting and testimony from his family and friends, together known as mitigating evidence, off set the factors that made the mass shooting especially heinous, and therefore a potential death-penalty offense.

Image James E. Holmes Credit... Arapahoe County Sheriff's Office

Prosecutors, emphasizing the human toll and indiscriminate cruelty of opening fire on a happy crowd of moviegoers, argued that Mr. Holmes should join the three other men on Colorado’s death row. Defense lawyers said it was not hatred or a desire for notoriety that compelled Mr. Holmes to plot and carry out the massacre, but a deepening form of schizophrenia that infected his mind with powerful delusions that killing people somehow increased his “human capital.”

Two court-appointed psychiatrists who examined Mr. Holmes — and who testified for prosecutors during the guilt phase of his trial — concluded that he was mentally ill, but was still able to know his actions were wrong when he strode heavily armed into a showing of a “Batman” movie, just after midnight on July 20, 2012, and began shooting at the crowd.

Nevertheless, the doctors said the shooting likely never would have happened were it not for Mr. Holmes’s mental illness. The defense seized on that point in arguing to spare Mr. Holmes’s life. But the jury did not buy it.

The sentencing now moves to a third phase in which victims’ families will have a chance to tell jurors about how their lives were ripped apart. After that, the jury will deliberate yet again to make its final decision whether to sentence Mr. Holmes to death or to life in prison with no parole.