Exactly. Somebody didn't make the least bit of effort to do their homework.
Something about this "friend of a friend" story seems fishy to me. How would the neighbors know whether the drone was registered? How did the "aviation police" (Is there such a thing? I don't think so.) get access to the drone to prove the friend of a friend even owned a drone, much less whether it had the registration on it?
"No, officer, I don't own a drone. Must be someone else in the neighborhood."
By the way, the OP had his questions in this thread answered in December when he had similar concerns back then: How Does the FAA know what drone I am flying?