Subd. 1. Tenure. A grand jury must be drawn for a specified period of service, not to exceed 12 months, as designated by court order. The grand jury must not be discharged, and its powers must continue until the latest of the following:
Subd. 2. Excusal. For cause shown, the court may excuse a juror temporarily or permanently. The court may impanel another person in place of the excused juror.
Minn. R. Crim. P. 18.08