John Rhode 
Body Unidentified 

Body Unidentified, first published in 1938 (and published in the UK under the title Proceed with Caution), is part of the series of mysteries featuring private detective Dr. Priestley. Author John Rhode, a pen name of Cecil Street (1884-1964), was a prolific writer of mostly detective novels, publishing more than 140 books between 1924 and 1961.From the dustjacket: Mr. Wedgwood was puzzled. It was odd, he thought, as he looked from his bedroom window, that someone should leave a large closed car in the middle of his front yard, but what confused him even more was the shimmering brilliance it seemed to assume as the sun rose higher. Suddenly the unpleasant truth burst upon him with a shock. It was not a car at all. It was a hearse! Jimmy Waghorn first followed the grisly trail from the abandoned hearse to the "thing" in the tar boiler, and as luck would have it, on that same day Inspector Hanslet finally stumbled on a really substantial clue to the Patton jewel robbery. But only after Dr. Priestley made his seemingly enigmatic suggestion did it occur to either one that the two crimes could possibly be related. Author John Rhode with his usual ingenuity and scrupulous care has worked two apparently diverse crimes into a fascinating pattern of mystery and intrigue.