W. Va. Code § 62-3-7: Filling vacancy in jury; discharge of jury.

If a juror, after he is sworn, be unable, from any cause, to perform his duty, the court may, in its discretion, cause another qualified juror to be sworn in his place. And in any criminal case the court may discharge the jury, when it appears that they cannot agree in a verdict, or that there is manifest necessity for such discharge.