[tomxtr]

My sense is this person is pretty comfortable stealing in front of you, which leads me to believe that you haven't voiced an objection to their face. If you had, they would have a)stopped doing it in front of you or b)stopped all together. So it seems to me that you're only considering telling now because you are involved, not because its the right thing to do. If you do tell, don't be a two faced asshole and play dumb. If you don't tell, don't bitch about your moral dilemmas if this is the kind of company you keep.