The Ox-Bow Incident (1943) - Rotten Tomatoes
A very good and still relevant movie about the abuse of power and the results of it.
Had seen this on a reel projector while still a high school student at Earl Wooster High School in 1975 or 1976.
The writer of the book of the same name-- Walter Van Tilburg Clark-- had grown up in Reno, Nevada and had taught at the University of Nevada, Reno.
Walter Van Tilburg Clark - Wikipedia