Yes, the police are very aware of the boyfriend and know about the stolen items and drug use. He has been arrested several times there. Never thought of adult protective services...that is a good idea. Thanks for the help!
Why on earth would you involve adult protective services? Is the daughter abusing the father? Are they living in filth or squalor?
Just because he can't confront the trash boyfriend doesn't mean you want to open the APS can of worms and end up harming the older tenant in the long run.
If the police have already been involved, you need to do your job as a business owner and trespass the guy from the property and let the police continue to do their job.
It's commendable that you want to help this old man, but you're now way too involved in this family's personal problems. If the father and daughter can't keep this person away, you may want to consider not renewing their lease the next time it's up.
Also this -
"stores stolen items in the laundry room (which we have thrown away many times)"
This is not your place to dispose of *anything* being stored in a rental. If you suspect stolen property or illegal substances, your duty as a landlord is to notify the police. Destruction of property will only get *you* in trouble. You technically have no proof that anything is stolen.
Tread carefully in this situation, and don't do anything to land yourself in trouble. Detach yourself emotionally from this.