Dianne, how horrible!!

The same people who would do something like that to an old man would probably hurt children and little puppies. They have names for people like that and they're not very nice.

If you're really serious about making this person accountable for this, I'd follow Chatty's advice and confidentially report them to the credit card company. If anything it'll redirect their collection efforts from your FIL to this person. Of course, they'll probably never collect. If this person had an ounce of decency, they'd step up and take responsibility.

I'm just sorry you have to go through this.