(a) A grand jury impaneled pursuant to subsection (a) or (c) of Kan. Stat. Ann. § 22-3001, and amendments thereto, shall serve until it shall advise the court in writing that it has completed its investigation, but no such grand jury shall serve for more than three months unless extended by order of the district court. The district court may, before the expiration of the tenure of such grand jury, make an order extending such grand jury for an additional period of not to exceed three months if the court finds that an investigation begun by such grand jury cannot be completed within the initial three months period and that the public interest requires the continuation of such grand jury.

(b) A grand jury impaneled pursuant to subsection (b) of Kan. Stat. Ann. § 22-3001, and amendments thereto, shall serve for a period of six months. The district court may, before the expiration of the tenure of such grand jury, make an order extending such grand jury for an additional period of not to exceed six months upon good cause shown by such grand jury.

(c) At any time for cause shown the court may excuse a juror either temporarily or permanently, and in the latter event the court may impanel another person in place of the juror excused.