I got a call from "John" from the American Police and Sheriffs Association as well - about a month ago. He asked firmly for money. I asked him to send me something in the mail. The very next day a woman called asking if I had promised to send money and that I would receive an envelop in the mail on Tuesday. I hung up on her.
This number called me yesterday to ask if I would donate to the police. The man who initially called then handed off the phone to a woman, which I thought was weird.
I said hello, he described what he was calling about. I said "ok" and then he said nothing else" I repeated "hello" a couple times but no response so I hung up. Very odd.