Holmes' lawyers called no witnesses and cross-examined only a few of those summoned by prosecutors during the hearing. But they pointedly raised the issue of Holmes' sanity at strategic moments, possibly foreshadowing a defense that some believe is his best hope to avoid the death penalty.
"You're aware that people can be found not guilty on the grounds of insanity?" defense attorney Daniel King asked one witness.
The preliminary hearing, which ended Wednesday, was designed to determine whether prosecutors' case is strong enough to put Holmes on trial.
Holmes' lawyers haven't said if he will plead not guilty by reason of insanity, but since his arrest outside the theater in the Denver suburb of Aurora immediately after the shootings, they have portrayed him as a man with serious mental problems prone to bizarre behavior.
Many legal analysts have said they expect the case to end with a plea bargain rather than a trial.
Tom Teves, whose son Alex was among the dead, said he would rather see Holmes plead guilty to first-degree murder, avoiding a traumatic trial, bringing a life sentence and closing the door to an insanity defense.
If found not guilty by reason of insanity, Holmes could conceivably be released someday if he is deemed to have recovered.
"Don't pretend he's crazy," Teves said Wednesday. "He's not crazy. He's no more crazy than you and I."
Prosecutors developed twin themes at the hearing: the horror and devastation of the attack, and a weekslong process in which they alleged Holmes planned and prepared for the assault.