I am not sure what the laws are where you live, but where I live, a person's legal residence is where they recieve mail. Even if they are not on the title, lease, or any of the utilities. (Found this out the hard way, removing someone from my own home) This makes them by law a month to month tenant, and requires 30days notice to be evicted. If he has not recieved any mail there, you may be able to prove that this is not his legal residence, but that may take more time and confrontation than you wish to invest. Make sure you do give him a written notice stating that he has to move out, just in case you need it.
I really am sorry you are getting stuck with him. Once you do get him out, it might be a good idea to get a restraining order if he gives you any greif.