This is a civil matter and is governed by landlord tenant law.  It is not appropriate to try and make this a criminal matter by summoning the police.  You need to start eviction proceedings to make him move out and pay the back rent he owes you.  For this you need an attorney.  If you cannot afford an attorney go to the county courthouse and talk to the clerks of court about how to do this yourself.  If there is a legal organization that offers service sto clients that cannot afford an attorney they will know about it.  Good luck!  Next time make sure you have a lease  with your tenants and a first and last month's deposit on account so this doesn't happen again.