Improved intrusion detection system and method

An intrusion detection system controller, including a restriction designator operable for pre-designating an individual for whom access to a portion of the premises is prohibited and, for each individual, pre-designating an individual-specific restricted portion of the premises to which access is prohibited; a designated individual presence ascertainer operable for ascertaining presence of a designated individual on the premises; an intrusion detector element communicator operable for communicating with detection elements, for receiving indications of detection of intrusions and, responsive thereto, for ascertaining an intruded portion of the premises and providing an output indicating detection of the intrusion in the intruded portion of the premises; and a restricted mode enforcer operable, responsive to ascertaining presence of the pre-designated individual and to receiving output indicating detection of the intrusion in the intruded portion, for ascertaining whether the intruded portion corresponds to the individual-specific restricted portion to which access of pre-designated individual is prohibited.