Abstract: A security system includes an entry monitoring sensor for detecting movement into a first space, a first area monitoring sensor for detecting occupancy in the first space, at least one area monitoring sensor for detecting occupancy in at least one space adjacent the first space. The system further includes a timing device for measuring a first time period in response to actuation of the entry sensor and for measuring a second time period in response to the actuation of the first area sensor during the first time period. An alarm device indicates any suspicious occupancy at the expiration of the second time period in the absence of detection of occupancy by at least one of the area sensors for detecting occupancy in at least one space adjacent the first space.