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 case, the court may discharge the jury when it appears that they cannot agree on a verdict or that there is a manifest necessity for such discharge.

Code 1950, § 8-208.23; 1973, c. 439; 1977, c. 617.