This paperback original, published by Ace Books, was half of a double-novel release. Turn the novel over, and you found Kill Me with Kindness, by J. Harvey Boyd. The Guilty Bystander was one of two novels Mike (or Michael) Brett wrote starring “bald-headed bookie”-cum-private eye Sam Dakkers; the other was Scream Street, also published in 1959. In addition to the Dakkers tales, Brett produced a longer-running series of novels led by Manhattan P.I. Pete McGrath (Kill Him Quickly, It’s Raining).