I don't know much about cops, but I would guess that the subset of skills that they use regularly matches up pretty well with the skills required to be a pilot.
-situation awareness
-operating a motor vehicle while multitasking
-communicating on the radio
-following rules and regulations
The nice thing about the engineer types is that you need only minimal ground time with them to teach things like how an airplane works-they already understand things like basic physics, electricity, etc. It does seem to take a while for them to get used to the multitasking and the rough-guessing required in an airplane. They like to have everything neat and precise.