I have seen pretty bad... I have to be cautious here and warn you because of the POTENTIAL repurcussions... the % of responses that are actually violtent are likley small, but I don't know WHAT he may do, I don't KNOW him at all... so I have to warn you just to be on teh safe side
I think you have to chck with the law befroe you change any locks don't you? Is the hosue just in your name or can you deny him entry legally?