The sitting duck [first edition]

From the cover: "Jack Sterling was an impossible bird--a canary who sang for the cops (thereby sending some dangerous criminal types to the slammer), and who thus became a sitting duck, especially when he returned to the scene, so to speak, of his "crime" --New York. George Bagby spotted him one evening while having a drink inn P.J. Somethinngorother, and it wasn't long before he passed the word to his friend Inspector Schmidt of Homicide. While speculating on the fate of sitting ducks and waiting for something to happen, it happened. And George Bagby finds himself launched on another fast-paced adventure--this time investigating the bizarre life and career, as well as the killing, of a very off bird indeed."