From the cover of Authentic Police Cases #17 (1952):
Yes, because horse race fixing is a much more serious crime than murder, right?
And murdering the groomsman or stable boy who helps you EVERY time you fix a race wouldn't be a clue to the cops that the race was fixed...
And they're caught because....well, they've been slipping spiked sugar cubes to the targeted horses. So our ace detective...well...
He has every restaurant in town stop serving sugar cubes. Because, apparently, these race fixers are so dumb, they can't just go to the grocery store and buy them. Or get some from their friends in the race industry. No, these mooks have to steal them from restaurants.
And the police plan is brilliant, because arresting patrons who ask for sugar cubes is a much more efficient strategy than, say, tracking down whoever has been netting on all the long shots who have been winning.
But these criminals are stupid, so the stupid plan works. Justice!!