It happened to me with a cousin. Report the charge as fraud. It gives him some time to pay it (like a month). If he doesn't, they start looking for the thieve or write it off. That way at least it isn't on you. Just tell him what you did and make sure he understands that you're not taking any responsibility for it. If he gives you the money, you can always call the CC company and say you figured it out and you'll be paying it. That's what I did with the $700 my cousin charged. I reported it as fraud and only after he payed me did I call the CC company and let them know it was taken care of and I'd be paying it. And I'm close to my cousins.