I don't know about all the states, nor do I know how the Kentucky State Police ( KSP ) are currently marking their issue guns, but I know that at least some of thier older issue guns were marked KSP. I bought a Smith and Wesson .45 auto ( don't remember model number ) from a sale that they had after they switched to a new gun. They sold all the ones in the armory they had been unissued and they were all marked with the KY state seal and KSP.

I'd think that a lot of states used to mark their older guns, getting one from every state would be quite a collection.