Upon final submission of the case to the jury, the alternate jurors shall not retire with the jury of 12 for deliberation but may be discharged. However, if the court deems it advisable, it may direct that one or more of the alternate jurors be kept in the custody of the sheriff or one or more court officers, separate and apart from the regular jurors, until the jury has agreed upon a verdict.
OCGA § 15-12-171