(a)
(1) At a hearing concerning a defendant's lack of criminal responsibility or fitness to proceed, or upon trial, an examiner who conducted an examination under § 5-2-327 or § 5-2-328 may be called as a witness by the prosecution, the defendant, or the court.
(2) If the examiner is called by the court, he or she is subject to cross-examination by the prosecution and by the defendant.
(b) Both the prosecution and the defendant may summon any other qualified physician or other expert to testify.