Abstract: A door locking mechanism of the chain guard type which can be used as a dead lock and in a manner similar to currently popular regular safety chain type door locks. The mechanism comprises a bolt keeper formed with at least one elongated slot terminating into at least one enlarged opening. A bolt matched in size and shape cooperates with this keeper and is inserted into the keeper through the opening and captively slides in it after insertion. The mechanism further includes a key operated lock having a lock member that can be secured to and released from the lock. A chain interconnects the lock member and the bolt and forms therewith a chain assembly having an operative length which is selectable between at least two positions. In one of these positions, the bolt can be removed from the keeper without freeing the lock member from the lock.