This was obviously a isolated situation.A year later the sheriff came and took it into evidence for a theft case.
By saying 'came and took it' I assume you mean came to your house? If so then the pawn shop did something right as there was a paper trail of the sale to you. Either someone made some kind of mistake or the gun was never flagged or reported as stolen.
I think everyone is overlooking thd fact when it comes to guns a pawn shop has to have an FFL and follow the same rules ANY gun dealer.
Two of these rules are the buyer/seller must have a Valid ID and the dealer needs to perform a prescribed background check of the gun to ensure it is not stolen.
My point being is a pawn shop has no more or less the ability for a mistake to be made than any gun dealer. The fact that it is a 'pawn shop'
Does not change anything and they must follow all federal gun laws as a licensed dealer.