We actually just discussed this question where it was asked in a different topical area. See:
http://community.blr.com/hr/forums/thread/5696.aspx
It is not likely that you owe this person anything now that they are not an employee anymore but in some states you may. Although the other discussion may be helpful, if someone from Florida cannot answer you authoritatively, then you should get an answer from an employment law attorney in FL.
On one hand, you don't have to discuss someone's cause of termination with them once they're gone. I know at least one consulting firm that doesn't give reasons when they terminate employment on behalf of their client. They just say, "Well Bob, I must inform you that your employment has been terminated," they gather badges, keys, etc, and send them on their way. I don't think, from a practical standpoint, that's a good idea. It raises suspicions in the former employee. Personally, I think the right thing to do is have a discussion and answer their questions carefully with full attention to each and every word you utter. They should leave your office with a very clear understanding of why they are no longer employed. In the best case scenario, they should also accept that it was the right thing for your company to do, as well. That's a nice way to handle the meeting you have when you tell them they aren't entitled to copies of anything but you wouldn't mind discussing the issue with them.
I would not respond to any written request that isn't attached to a subpoena, although I might be inclined to share the written request with counsel if, as in this case, I wasn't certain about my obligations.