A method is provided. The method includes: establishing a database of a plurality of individuals, data for each individual including identity, short range wireless device information, and at least one rule regarding expected interaction by the individual relative to the area; receiving probe signal information from a plurality of sensors around an area, each of the sensors being configured to receive probe signals from proximate wireless devices, the probe signals lacking information directly identifying an owner of the originating wireless device; cross referencing at least some of the received probe signals with at least a portion of the database; identifying, based at least on the cross referencing, a presence of an unauthorized individual in the area; and notifying a supervising authority of the identified unauthorized individual.