looking for a book

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I recently heard about a newly published book, but was unable to get title or authors name, so I hope somebody will recognise the story! Its about a policeman in New York(?) , probably during the 1920s. He was the only policeman in Amercia to have been sentanced to death for murder, and the general view was that he was set up, and probably was innocent, though was crooked in other respects. I think he had a farming background and was from a european family, maybe german. Thanks!