A method and apparatus for marking positions for burglar alarm sensor elements on a door, the door attached to a frame having a header including comprising the steps of providing a marking apparatus the marking apparatus including an arm arm, a positioning member with a longitudinal centerline attached to the arm, and punch point attached to the positioning member, the punch point being aligned with the longitudinal centerline of the positioning member; at least partially opening the door; placing the positioning member in a hole in the header and closing the door; while the door is closed causing the positioning member to make a mark on the top of the door; and opening the door and removing the positioning member from the hole in the header; and causing an opening to be made in the door at the location of the mark.