DENVER -- The long journey toward a verdict in the deadly Colorado theater shootings enters a new and critical phase Monday when the shooting suspect asks a judge to change his plea to not guilty by reason of insanity.
The plea is widely seen as suspect James Holmes' best hope, and perhaps his only hope, of avoiding the death penalty. But his lawyers have held off until now, fearing a wrinkle in the law could cripple their ability to raise his mental health as a mitigating factor during the sentencing phase.
Two judges have refused to rule on the constitutionality of the law, saying the attorneys' objections were hypothetical because the suspect had not pleaded insanity. The defense had little choice but to have him enter the plea and then challenge the law.
The suspect's lawyers announced last week that he would ask to change his plea at Monday's hearing.
Prosecutors are seeking the death penalty. They say the suspect, a former neuroscience graduate student, spent months acquiring weapons and ammunition, scouting a theater in the Denver suburb of Aurora and booby-trapping his apartment.
Then on July 20, dressed in a police-style helmet and body armor, he opened fire during a packed midnight showing of "The Dark Knight Rises," prosecutors say. Twelve people died and 70 were injured.
No motive has emerged in nearly 10 months of hearings, but the suspect's attorneys have repeatedly said their client is mentally ill. He was being treated by a psychiatrist before the attack.
The insanity plea carries risks for both sides. The suspect will have to submit to a mental evaluation by state-employed doctors, and prosecutors could use the findings against him.
"It's literally a life-and-death situation with the government seeking to execute him and the government, the same government, evaluating him with regard to whether he was sane or insane at the time he was in that movie theater," said attorney Dan Recht, a past president of the Colorado Criminal Defense Bar.
Among the risks for prosecutors: They must convince jurors beyond a reasonable doubt that the suspect was sane. If they don't, state law requires the jury to find him not guilty by reason of insanity.
"That's a significant burden on the prosecution," Recht said.
If acquitted, the suspect would be committed to the state mental hospital indefinitely.
A judge entered a standard not guilty plea on his behalf in March, and he needs court permission to change it. Recht said it's a foregone conclusion the judge will accept the new plea to preclude appeals later.
The mental evaluation could take weeks or months. Evaluators will interview the suspect, his friends and family, and if the suspect permits it, they'll also speak with mental health professionals who treated him in the past, said Dr. Howard Zonana, a professor of psychiatry and adjunct professor of law at Yale University.
Evaluators may give the suspect standardized personality tests and compare his results to those of people with documented mental illness. They will also look for any physical brain problems.
Zonana estimates he has conducted around 200 mental evaluations of criminal defendants, including some death penalty cases.
"All cases are tough," he said.
Meticulous planning, as in the scenario prosecutors laid out against Holmes, doesn't necessarily mean a defendant is sane, Zonana said.
Zonana said he helped evaluate Stephen Morgan, who was found not guilty by reason of insanity in the 2009 shooting death of Johanna Justin-Jinich in Middletown, Conn., where she was attending college.
Evidence showed Morgan planned the shooting, Zonana said, "but he was delusional."