Abstract: A high security lock of the type having a base, a bolt which moves on the base and engages a strike, and a dead lock tripper which interacts with the strike to automatically lock the bolt is improved by including a lock prevent member in association with the bolt. The lock prevent member inhibits the bolt from moving from an unlocked to a locked position in spite of the dead lock tripper interacting with the strike. A secondary key can be used to inactivate the lock prevent member such that the lock returns to its normal mode of operation with the interaction of the dead lock tripper and the strike automatically locking the lock.