ARS 13-407A: A person or his agent in lawful possession or control of premises is justified in threatening to use deadly physical force or in threatening or using physical force against another when and to the extent that a reasonable person would believe it immediately necessary to prevent or terminate the commission or attempted commission of a criminal trespass by the other person in or upon the premises.
B. A person may use deadly physical force under subsection A only in the defense of himself or third persons as described in sections 13-405 and 13-406.
C. In this section, "premises" means any real property and any structure, movable or immovable, permanent or temporary, adapted for both human residence and lodging whether occupied or not.
I'd say your good. As long as he was told to leave first, or the property is posted.