The Rifleman S01E21 - The Indian

Lucas McCain and his son Mark come across U.S. Deputy Marshal Sam Buckhart who is escorting an Indian prisoner. To Lucas' surprise he finds that Buckhart himself is an Indian, educated at Harvard College. In North Fork, Buckhart goes about his business until some of the townsfolk realize he is an Indian and decide to take matters into their own hands. It's left to Lucas to show them the error of their ways.