Georgia Code Title 17. Criminal Procedure § 17-7-130.1

At the trial of a criminal case in which the defendant intends to interpose the defense of insanity, evidence may be introduced to prove the defendant's sanity or insanity at the time at which he is alleged to have committed the offense charged in the indictment or information. When notice of an insanity defense is filed, the court shall appoint at least one psychiatrist or licensed psychologist to examine the defendant and to testify at the trial. This testimony shall follow the presentation of the evidence for the prosecution and for the defense, including testimony of any medical experts employed by the state or by the defense. The medical witnesses appointed by the court may be cross-examined by both the prosecution and the defense, and each side may introduce evidence in rebuttal to the testimony of such a medical witness.