(1) Any Chief Circuit Judge may summon for cause a special grand jury to deal with a situation requiring lengthy investigation which cannot be adequately handled during the term of the regular grand jury.
(2) A special grand jury shall remain in session until discharged by the court, but shall not remain in session longer than ninety (90) days, provided, however, that a special grand jury may be extended for additional ninety (90) day periods on the written order of the Chief Circuit Judge.