Legal Question in Landlord & Tenant Law in California

You don't say how you gave the 3 and 30-day notices, so I can't say if they are enforceable or not, which is the starting point of what you can and can't do. In any case, unless he physically vacates the premises, you have to go through the unlawful detainer process. You cannot keep his posessions to offset the rent in any case. If he abandons the posessions there is a process for removing and disposing of them. Since he comes by and gets his mail, it seems you do, in fact, have a way of contacting him, both by posting things on the door of the unit, leaving things in a conspicuous location in the unit, and leaving things in the mailbox. So do not expect a court to accept an argument that you couldn't contact him. I suggest you pick up the Nolo Press book on handling evictions: http://www.nolo.com/products/the-california-landlords-law-book-LBEV.html And "do it by the book." If you need further help, let me know. I'm a small-time landlord with a property in Piedmont, and have had to get rid of one tenant a couple of years ago. So I not only am a lawyer but I've "been there done that."

Assuming your notice is proper, the next step is to file an unlawful detainer lawsuit in court, have it served on the defendant, and proceed to judgment. Once you obtain a judgment, you can legally evict him. Otherwise, you're just spinning your wheels.

I assume you properly served the 3 day notice to pay or quit. If you did and he is gone after 3 days then you could rightly fully and reasonably assumed he did what you asked which is to leave. In that case I would post a big notice on the door informing him as well as mailing it that it appears he was abandoned the property, you are going to change the locks and put his stuff in storage unless he calls you or gives you his address. If he fails to contact you after a couple of days I would go ahead and change the locks and see what happens. If he objects then give him the new keys along with the summons and complaint in the eviction action that you will quickly file so someone can get it to him with the keys. Otherwise he will evade service.

Also Tim made an excellent suggestion about the Nolo Press Book, sometimes I even look I there.

Hope this helps and good luck.