US judge accepts James Holmes' insanity plea for trial in 'Dark Knight' movie massacre case

A US judge has agreed to James Holmes use of 'Joker defense' to argue he is not guilty by reason of insanity for allegedly carrying out the 'Dark Knight' movie theater massacre.

Holmes had allegedly killed 12 people during the screening of 'The Dark Knight Rises' at a movie hall in Colorado, United States, last year.

According to the New York Daily News, a judge on Tuesday accepted Holmes' plea, setting the stage for a lengthy mental evaluation of the suspect in the shooting.

Judge Carlos Samour Jr. read through 18 points regarding the nature of the plea in court, and then asked Holmes if he had any questions.

Defense attorney Daniel King arrives at district court for a hearing for Aurora theater shooting suspect James Holmes in Centennial, Colorado, on Tuesday.

The judge said that he found Holmes understanding the effects and consequences of the not guilty by reason of insanity plea, adding that he was looking at the advisement and appeared to be following along, the report said.

According to the report, Holmes' lawyers repeatedly have said he is mentally ill, but they delayed the insanity plea while arguing state laws were unconstitutional.

The next step will be to carry out a psychiatric evaluation of Holmes by state doctors to determine whether he was insane at the time of the shootings, which could take months.

If a jury finds Holmes not guilty by reason of insanity, he would be committed indefinitely to the state mental hospital, the report added.