1.) Call the police and file a report about him. 2.) If people solicit you at your business, claiming to do legal work, that's going to be a scam 99.99% of the time. 3.) To answer your question, if he's an identity thief, he could try to get into your bank accounts or get credit in your name. If he's a regular thief, he might try to break into your home (now he has your address) or your business. Or...he might give up and move on to the next target.
I'm not your attorney. By offering "answers" on Avvo, I am doing nothing more than providing an opinion for informational or educational purposes only.