Polo's Ponies

There was no doubt about the murder weapon. You could see the outline of the horse's hooves...

But that was the second murder. When San Francisco private investigator Nick Polo rejoins his date at the races after a rather prolonged trip to the men's room, the first thing she says is "Are you feeling all right?" And the second is "Your zipper's undone." There is reason for both. Polo is not looking too well, and quite understandably. He'd just discovered the dead body of one of his Uncle Pee...