Abstract: A locking arrangement with built-in alarm mechanism utilizing a contact between portions of a split bolt arrangement as the prime security measure is described. Correct sequencing of both the locking and unlocking actions is required to prevent alarm. Two realizations are described: a self-contained unit for building doors; and an automobile unit with central alarm, alarm sensors for ignition and other locations subject to tampering (hood, trunk, battery), and a set resistance method to prevent disarming by either circuit opening or shorting techniques.