Police Your Planet ♦ By Lester del Rey

Bruce Gordon was an ex-fighter, ex-gambler, ex-cop, ex-reporter, and now he was an ex-patriot of Earth. Security shipped him to Mars with a knife, 100 credits, and a yellow card that meant no return. An SF novel that would appeal to Mickey Spillane fans, Police Your Planet features lots of hands-on violence, assorted beatings, and blood. But this isn't just a crime novel put into space; this is a hard sf novel, and the terraforming of Mars, while not dwelt upon, is central to the story.