N.H. Rev. Stat. Ann. § 24:17

The county convention by a vote of a majority of all its members may appoint a committee of its own members, not to exceed 5, and not over 3 to be of either of the 2 major political parties, to investigate conditions pertaining to the conduct of county affairs by any county officer or any person appointed or employed by such officer, which committee shall have power to summon witnesses, examine them under oath, secure a transcript of the testimony and do other necessary acts to conduct such an investigation.