"Patrolman" is a word in LAW AND LEGAL, ENGLISH

A policeman assigned to duty in patrolling a certain beat or district; also the designation of a grade or rank in the organized police force of large cities, a patrolman being generally a private in the ranks, as distinguished from roundsmen, sergeants, lieutenants, etc. See State v. walhridge, 153 Mo. 194, 54 S. W. 447

One who patrols; a watchman; especially, a policeman who
patrols a particular precinct of a town or city.