so he's returning the card out of the goodness of his heart and despite the fact he lost not only what he paid for the card but also money from his own wallet.
If I believed the other person needs it more than I do and was not responsible, I would.
Besides, if he was the thief and he returns the card, what has he gained? Just the BTC, right? They would both be back to where they started - Kennji would have his card back and the thief would have just stolen his own bitcoins back.
He's only returning the card because he was caught.
I can't believe how people on here seem to want to go for the most elaborate scenario possible when it's obvious what happened. Anyway good luck to the op.
THIS. The whole "oh some malware got on his USB stick and it autoran on your computer" is sooooo unlikely, that is not how most malware is spread whatsoever, and most people have USB autorun off, I think it's off by default in most modern Windows installs.
The argument of "he didn't do this scam in the same way that many thieves do scams!" is just silly, there are tons of novice criminals, dumb criminals, etc., and it's even possible that he had only vaguely thought of it before, but once he was there and you left the room, he went "ah why not".
Anyhow, if the guy claims he ALSO had coins stolen at the same time, I'd like to see him prove that, show a transaction at the same time from an address he can prove is his. THEN maybe I'd start to believe him.
gl OP