The sheriff shall keep and preserve the peace of the county, for which purpose the sheriff may require the aid of such persons or power of the county as the sheriff deems necessary. The sheriff shall also pursue and apprehend all felons, execute all processes, writs, precepts, and orders issued or made by lawful authority and to the sheriff delivered, attend upon the terms of the district court, and perform all of the duties pertaining to the office, including investigating recreational vehicle accidents involving personal injury or death that occur outside the boundaries of a municipality, searching and dragging for drowned bodies, and searching and looking for lost persons. When authorized by the board of county commissioners of the county the sheriff may purchase boats and other equipment including the hiring of airplanes for search purposes.