N.H. Rev. Stat. § 5-C:55

I. If an individual believes a bigamous marriage has taken place and such individual wishes to challenge the validity of the marriage certificate, the individual making the accusation shall provide to the clerk of the town or city a notarized statement of the alleged facts; a copy of the marriage certificate from the accused individual's previous marriage that was allegedly not dissolved; and a notarized affidavit from the spouse in the previous marriage attesting that the marriage was not dissolved. The clerk of the town or city shall prepare the appropriate form and have the person making the accusation sign the form in accordance with RSA 5-C:85. The clerk of the town or city shall forward the notarized statement and all other related documents to the state registrar. II. The state registrar shall send a letter via certified mail to the accused stating the alleged facts and requesting documentation to prove the marriage certificate in question is valid and dispute the claim of bigamy such as, but not limited to a certified copy of a final divorce or civil annulment of the previous marriage or a death certificate of the spouse from the previous marriage. If the division does not receive a response to the certified letter within 30 days of the signed receipt of the letter, the state registrar shall inform the person making the initial allegation of the lack of response and the need to refer the matter to a court of competent jurisdiction. Upon receipt of the evidence submitted by the accused, the state registrar shall determine whether the validity of the marriage certificate is in question. If the evidence submitted shows that the validity of the marriage certificate is not in question, then the state registrar shall send a certified letter to the accused with the results of the investigation and a copy of the letter to the person making the allegation and the clerk of the town or city. If the evidence submitted shows that the validity of the marriage certificate is in question, then the state registrar shall send a certified letter, indicating the results of the investigation and that the marriage certificate shall be voided, to the accused, the person making the allegation, and the clerk, and the county attorney. In the case where the accused disputes the determination of the state registrar, the accused may request, within 30 days, an administrative hearing. All material forwarded by the clerk of the town or city including the affidavit of the information and any pertinent documents shall be retained by the division.