Va. Code Ann. § 19.2-154

If by reason of death, sickness or other disability the judge who presided at a criminal jury trial is unable to proceed with and finish the trial, another judge of that court or a judge designated by the Chief Justice of the Supreme Court or by a justice designated by him for that purpose, may proceed with and finish the trial or, in his discretion, may grant and preside at a new trial. If by reason of such disability, the judge who presided at any trial is unable to perform the duties to be performed by the court after a finding of guilty by the jury or the court, another judge of that court, or a judge designated as provided in the preceding sentence, may perform those duties or, in his discretion, may grant and preside at a new trial. Before proceeding with the trial or performing such duties, such judge shall certify that he has familiarized himself with the record of the trial.