There was another similar incident, where a woman bought two iPhone 5s off another woman (they met at a McDonald's to do the transaction). The purchaser didn't check the contents before handing over the cash, so when she got home, she got quite a nasty surprise when she found an apple (the edible fruit) inside each iPhone box.
Paypal, typically takes the word of the buyer, and "affidavits" from others are not needed - unless the OP will get the police involved.when you file the claim be sure to give them a picture of the box of paper. It may also be helpful if there was a witness when you opened the box so it is not just your word vs the other person. Treat the box, contents, and packaging materials as evidence of a crime....because they are.