N.H. Rev. Stat. Ann. § 7:33-b

With the approval of the applicable county commissioners and attorney general, a county attorney is hereby authorized to employ a contract assistant county attorney to assist the county attorney whenever the criminal dockets are backlogged with caseloads such as to make it expedient to do so. The compensation for such officer shall be fixed by the executive committee of the county convention and shall be on a per diem basis.