You are a Security Guard at a Mall and walking the parking lot when you see?

You don`t mention if there are any cameras...if there were you could say his actions then and now are being recorded and could be used against him later on...tell him if he chooses to ignore your verbal warning you will have to take it further...put the ball in his court....walk away ...and if he follows you keep on walking in the direction of the other guard...if he attempts to block your way just get on the radio and ask for some sort of back up..