A locking device assembly for a door located at a door frame. The locking device assembly includes a door strike assembly including a magnetized ferromagnetic material and a latchbolt assembly located at the door. The latchbolt assembly includes a latchbolt and a magnetic field sensor, wherein the magnetic field sensor senses a magnetic field provided by the door strike assembly. The door strike assembly includes, in different embodiments, a magnet located in a frame of the door strike assembly or a magnetic roller. The magnetic field sensor includes a magnetometer configured to determine the presence of a magnetic field provided by the door strike assembly. In the event that the door strike assembly has been removed to defeat the locking device, the lack of the magnetic field indicates that a security condition exists. An alert is provided to indicate the existence of the security condition.