CENTENNIAL, Colo. — In the nearly eight months since James Holmes first shuffled into court with vacant eyes and reddish-orange hair, neither he nor his lawyers have said much about how he would plead to charges from the deadly Colorado movie theater shooting.

There have been plenty of hints, however. As his hair turned more natural-looking and his demeanor more even at court hearings, Holmes’ lawyers repeatedly raised questions about his mental health, including a recent revelation that he was held in a psychiatric ward for several days last fall, often in restraints, because he was considered a danger to himself.

If, as many expect, they enter a plea of not guilty by reason of insanity on his behalf Tuesday at a hearing that’s underway, it will clarify the court battle ahead: Was Holmes, 25, legally insane — unable to tell right from wrong — at the time of the shootings?

Pleading insanity could be the only way he can avoid life in prison or execution, given the evidence that has emerged so far, some legal experts said.

Prosecutors laid out a case that Holmes methodically planned the shooting for months, amassing an arsenal and elaborately booby-trapping his apartment to kill anyone who tried to enter. On the night of the attack, they say, he donned a police-style helmet, gas mask and body armor, tossed a gas canister into the seats and then opened fire.

The attack killed 12 people and injured 70 others.