CENTENNIAL, Colo. — The judge in the Colorado theater shootings case on Thursday indefinitely postponed the trial of James Holmes so attorneys can argue whether he should undergo further psychiatric evaluation.

Holmes’ trial had been scheduled to begin with jury selection in February.

Holmes, 25, pleaded not guilty by reason of insanity to charges of killing 12 people and injuring of 70 during a packed midnight showing of a Batman film at a suburban Denver theater in July 2012.

Prosecutors are seeking the death penalty.

Holmes underwent a mandatory sanity evaluation at the state hospital last summer. The results haven’t been made public, but prosecutors said Thursday they want a review of one of three conclusions. They did not elaborate, and both sides are barred from speaking about the case outside court.

Karen Steinhauser, a former federal prosecutor now in private practice, said most court-ordered sanity evaluations look at whether the defendant is mentally competent to stand trial; has an impaired mental condition or mental illness; and was insane at the time of the crime.

Colorado law defines insanity as the inability to tell right from wrong, so a defendant could have a mental illness but still be legally sane.

Steinhauser, who is not involved in the Holmes case, said the prosecution’s request for further evaluation might indicate that Holmes was found sane but with an impaired mental condition.

If that is the case, it could be difficult for prosecutors to convince a jury to convict him of murder and sentence him to death because of the difficulty in making the distinction between mental illness and insanity.

Arapahoe County District Judge Carlos A. Samour Jr. ordered both sides to submit written arguments on further psychiatric evaluation and tentatively scheduled hearings for Dec. 17 and 18.

Longtime Denver defense attorney Dan Recht said he is not aware of a Colorado judge ever granting a prosecution request for a second sanity evaluation.

Defense lawyers said in March that they might have their own doctors evaluate Holmes, but they haven’t confirmed whether they did so. The attorneys have acknowledged he was the shooter but said he was “in the throes of a psychotic episode.”

If jurors were to find that Holmes was insane, he would be committed indefinitely to the state hospital. If doctors there ever concluded Holmes’ sanity had been restored, he could one day be released, but that is considered unlikely.

Law enforcement officers have testified that Holmes planned the attack for months, stockpiling guns and ammunition. They also say he elaborately booby-trapped his apartment with bombs designed to explode and divert police and fire crews from the theater.

Prosecutors want to use that evidence to undermine the insanity claim by showing the attack was meticulously planned and that he knew it was wrong.