N.H. Rev. Stat. § 597:6-d
If it appears from an affidavit filed by a party that the testimony of a person is material in a criminal proceeding, and if it is shown that it may become impracticable to secure the presence of the person by subpoena, a justice of the court in which the defendant will be tried may order the arrest of the person and treat the person in accordance with the provisions of RSA597:2. No material witness may be detained because of inability to comply with any condition of release if the trial testimony of such witness can adequately be secured by deposition, and if further detention is not necessary to prevent a failure of justice. Release of a material witness may be delayed for a reasonable period of time until the trial deposition of the witness may be taken.
RSA 597:6-d
1988, 110:5. 1989, 386:5, eff. June 5, 1989.