Batman cinema gunman James Holmes asked police: "There weren't any children hurt, were there?" hours after his arrest.

A dazed-sounding Holmes asked the question in a video played for jurors, which showed two detectives interviewing him at the Aurora Police Department in Colorado about two hours after the July 2012 attack, which killed 12 people and injured 70 others.

Detective Chuck Mehl said later Holmes had seen a Crimes Against Children Unit sign in the police station, which might have prompted the question.

Detectives did not answer Holmes' question directly, but said: "We'll get to that."

Holmes, 27, has pleaded not guilty by reason of insanity to 166 counts including murder and attempted murder at the Aurora cinema complex which was showing the Batman film The Dark Knight Rises.

His lawyers acknowledge he was the gunman but say schizophrenia had so distorted his mind that he could not tell right from wrong.

Prosecutors say Holmes was sane and are asking jurors to convict him and sentence him to death.