Section 21-402 - Calling grand juryA. In a county with a population of two hundred thousand persons or more a grand jury shall be called every four months each year by the presiding judge of the superior court. Each grand jury shall sit until a new grand jury has been impanelled to replace it or until its term expires pursuant to section 21-403. Additional grand juries shall be called on petition of the county attorney stating the reasons therefor.B. In a county with a population of less than two hundred thousand persons the presiding judge of the superior court may call a grand jury either: 1. If, in the judge's sole discretion, the judge determines the public interest requires a grand jury.2. On petition of the county attorney.