CCRP 561     

Art. 561.  Change of plea of "not guilty" to "not guilty and not guilty by reason of insanity"

The defendant may withdraw a plea of "not guilty" and enter a plea of "not guilty and not guilty by reason of insanity," within ten days after arraignment.  Thereafter, the court may, for good cause shown, allow such a change of plea at any time before the commencement of the trial.