Erle Stanley Gardner 
The D.A. Holds a Candle [EPUB ebook] 

Douglas Selby, the ambitious young District Attorney of the territory around Madison City, had up before him a young man guilty of embezzling a comparatively small sum of money which he had spent gambling. Selby could have locked him up – and perhaps ruined his life. But he wanted to find the how and the why of this otherwise law-abiding young man’s gambling. Selby’s investigations led him to a hit-and-run motorcycle accident, to blackmail, and to the doorstep of De Witt Stapleton, the local big-wig, who ran things in that part of the country by and for himself.