N.H. Rev. Stat. Ann. § 613:2-a

A justice of the peace, upon receipt of a certificate of the clerk of a court of record in any jurisdiction contiguous to the state of New Hampshire that a criminal prosecution is pending in such court, and that a resident of this state is supposed to be a material witness therein, shall issue a summons requiring such person to appear and testify at the court in which such case is pending.