N.H. Rev. Stat. Ann. § 7:34

The county attorney of each county shall be under the direction of the attorney general, and, in the absence of the latter, he or she shall perform all the duties of the attorney general's office for the county. If no other representation is provided, under the direction of the county commissioners he or she shall prosecute or defend any suit in which the county is interested. The county attorney shall tax all costs arising in state or county suits in his or her county for the consideration of the court.