(1) All parties may stipulate that the jury may be selected up to thirty-one days prior to the date of trial. The stipulation must be unanimous among all parties and evidenced by a joint stipulation to the county court.
(2) In all cases, except as may be otherwise expressly provided, the accused shall be tried by a jury drawn, summoned, and impaneled according to provisions of the code of civil procedure, except that whenever in the opinion of the court the trial is likely to be a protracted one, the court may, immediately after the jury is impaneled and sworn, direct the calling of one or two additional jurors, to be known as alternate jurors. Such jurors shall be drawn from the same source and in the same manner, and have the same qualifications as regular jurors, and be subject to examination and challenge as such jurors, except that each party shall be allowed one peremptory challenge to each alternate juror. The alternate jurors shall take the proper oath or affirmation and shall be seated near the regular jurors with equal facilities for seeing and hearing the proceedings in the cause, and shall attend at all times upon the trial of the cause in company with the regular jurors. They shall obey all orders and admonitions of the court, and if the regular jurors are ordered to be kept in the custody of an officer during the trial of the cause, the alternate jurors shall also be kept with the other jurors and, except as hereinafter provided, shall be discharged upon the final submission of the cause to the jury. If an information charging a violation of section 28-303 and in which the death penalty is sought contains a notice of aggravation, the alternate jurors shall be retained as provided in section 29-2520. If, before the final submission of the cause a regular juror dies or is discharged, the court shall order the alternate juror, if there is but one, to take his or her place in the jury box. If there are two alternate jurors the court shall select one by lot, who shall then take his or her place in the jury box. After an alternate juror is in the jury box he or she shall be subject to the same rules as a regular juror.