As the father of an adult with a severe mental illness, I am dismayed by a Colorado prosecutor’s decision to seek the death penalty in the Aurora movie theater attack.

Attorneys for the accused gunman, James Eagan Holmes, offered to have their client plead guilty in return for a life sentence without parole. That was not good enough for Arapahoe District Attorney George Brauchler.

After consulting with “800 victims and their families” on the July shootings that left 12 dead and dozens wounded, Brauchler declared that for Holmes, “justice is death.”

Only the most egregious cases should merit the death penalty, and despite the monstrosity of these shootings, executing a defendant who was receiving psychiatric care and who appears to have a severe mental illness violates that high standard.

Although a definitive diagnosis has yet to be made public, Holmes was seeinga doctor who specializes in treating schizophrenia. News reports say Holmes told a fellow college student before the murders that he had been diagnosed with dysphoric mania, a form of bipolar disorder. Common symptoms for both schizophrenia and dysphoric mania can include delusions and impaired reasoning. Both illnesses frequently surface in men during their early 20s. The causes of both are unknown but are not thought to be brought on by an individual’s own actions.

My son got sick when he was 22. Chances are, you too know someone with a mental illness. Those of us with mentally ill family members have seen how schizophrenia and bipolar disorder can distort our loved ones’ thinking and sometimes cause them to break the law. Their actions are symptoms of their disorders.

Mental illness does not excuse murder — a fact that Holmes’s attorneys readily acknowledged. But murders spawned in psychosis should be adjudicated differently from those for profit, jealousy or revenge.

Our legal system does a poor job in dealing with mentally ill defendants. The standard legal test is whether the defendant knew at the time of the crime the difference between right and wrong and whether he understood the consequences of his actions. But that’s often a fool’s reasoning when applied to an ill person’s mind. I once asked a convicted murderer with schizophrenia whether he understood that murder was wrong and that if he murdered someone, he would be punished. Of course he did, he quickly replied to both questions: “Everyone knows you shouldn’t kill people. I didn’t kill anyone. I killed an alien that had crawled into a baby’s body. I saw it go inside him.”

Brauchler’s Pontius Pilate-style explanation does not absolve him of his prosecutorial responsibility to use discretion in the face of public cries for blood. Nor is Brauchler, an elected official, delivering “justice” to the victims and their families. Sending Holmes to prison for life without parole would have brought swift closure while ensuring public safety. Now victims face a protracted public trial, decades of legal appeals and appellate hearings in which they will be required to rehash their nightmares.

Federal prosecutors agreed to spare the life of Tucson mass murderer Jared Lee Loughner, who was diagnosed with paranoid schizophrenia, after he pleaded guilty and accepted a sentence of life without parole for killing six and wounding 13, including Rep. Gabrielle Giffords.

Arapahoe County prosecutor Brauchler should have followed suit. Instead, he chose a road that will add more pain to an already unbearable tragedy.