It sounds like you could file a lawsuit against the tenant and owner of the adjacent building, but of course there is an evidence problem because you'd have to show that you're correct.Without knowing more, I'd suggest two things. First, setting up surveillance might help. Second, if you send the owner of the adjacent building a letter asking the owner to pay for the damage to your building and see that it does not continue, that might inspire that owner to have a word with its tenant. That owner probably has a lot more power than you do to get quick results.That's a practical opinion, not so much a legal one. You can always file a police report, for what those are worth.