In the 1st room, he doesn't do any damage to you. From the 3rd room (after he sees you or you aggro him) he shoots through both glass doors and the walls. Sometimes after entering the 3rd room, I think he becomes invisible. If not he almost instantly goes to the 2nd room and again shoots throught he glass doors/walls.
On a side note, all the npcs there seem to be able to move through the boxes by the 1st to 2nd room glass doors.
