Guard inmates in penal or rehabilitative institutions in accordance with established regulations and procedures. May guard prisoners in transit between jail, courtroom, prison, or other point. Includes deputy sheriffs and police who spend the majority of their time guarding prisoners in correctional institutions.
United States Department of Labor
Occupational Employment and Wages
05/15/2019
https://www.bls.gov/oes/current/oes333012.htm#st