AU2009201984B2 - Security system and method - Google Patents

Abstract

A security system for marking an intruder in an area with a marking agent is disclosed. In an embodiment the system includes a reservoir, a sensing circuit and an 5 outlet coupled to the reservoir. The reservoir contains a volume of a marking agent. The sensing circuit detects an intrusion into the area and momentarily enables a control signal for a predetermined duration in response to detecting the intrusion. The outlet is activatable in response to the enabling of the control signal to release into the area a quantity of the volume of the marking agent from the reservoir. A method of marking an 10 intruder in an area with a marking agent is also disclosed. 108 -+V ---- L----- GND + SENSOR]

Description

P/00/0011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: SECURITY SYSTEM AND METHOD Applicant: DOTTI ENTERPRISES PTY LTD The following statement is a full description of this invention, including the best method of performing it known to me: 2 SECURITY SYSTEM AND METHOD This application claims priority from Australian provisional patent application 2008902495 filed on 20 May 2008, the contents of which are to be taken as incorporated 5 herein by this reference. FIELD OF THE INVENTION The present invention relates to a security system and method. In a typical application, an embodiment of the security system may be used to assist in identifying an intruder into an area monitored by the system. 10 BACKGROUND OF THE INVENTION Security systems for detecting an intrusion into a premise or vehicle are becoming increasingly sophisticated. Indeed, modern systems typically involve complex sensor networks, such as infra-red detectors, reed switches, and the like. Typically, intrusion detection systems are configured to activate an alarm signal, 15 such as an audible alarm or a visible alarm signal, on detection of an intruder. Some systems may also communicate with a remote monitoring service which may then initiate action in response to the activation of the alarm signal. Activation of the alarm signal may be sufficient to cause an intruder, such as a thief, to abandon their activities and leave the monitored premise or vehicle. 20 Alternatively, police or other security personnel may be notified, either by the alarm signal or a remote service, and subsequently investigate the cause of the activation, which may lead to apprehension of the intruder. However, in either case the perpetrator is provided with an opportunity to leave the premise or vehicle, and thus avoid immediate apprehension, thus requiring an investigating authority to rely on evidence which may 25 have been left at the scene, or detailed witness accounts, in order to subsequently identify the perpetrator once apprehended. Unfortunately, witness accounts are frequently unavailable (or unreliable) and the evidence may not be unequivocally traceable to a particular individual. In addition, intruders often take care to ensure that evidence is not left at a crime scene. 30 Security systems exist which capture or record "evidence", either by continuously monitoring an area or on activation of an alarm signal. For example, some intrusion detection systems often employ video cameras which capture video images of a monitored zone and thus that may record an image of a perpetrator. Other security systems may be activated to record audio effects from a monitored area so as to 35 possible record an intruder's voice for subsequent analysis. Although such systems may, 3 for example, provide an image of a perpetrator, the image alone may not be sufficient to unequivocally identify an intruder, especially in cases where a perpetrator is disguised. Recently, security systems have been developed which can be activated to "mark" a perpetrator with a marking agent which can subsequently be used to assist in 5 establishing that a particular individual was present within an environment monitored by the security system. In such systems, the marking agent is continuously sprayed into a monitored area on activation of the alarm until the supply of the marking agent has been exhausted. One example of a "marking" system is disclosed in U.S. Pat. No. 5,763,176. In 10 this system an aerosol device is activated to spray an intruder with a unique microtrace label. Unfortunately, systems of the type disclosed in US. Pat. No. 5,763,176 are not well suited for intrusion detection applications since an intruder may be able to use techniques which deliberately activate or fool the aerosol device into spraying the entire 15 contents of the aerosol device whilst the perpetrator is outside of the area to be "sprayed". For example, in the case of vehicle, an intruder may use techniques to trigger the aerosol device from outside of the vehicle, causing the aerosol device to spray its entire contents before the intruder has entered the vehicle. In other words, the aerosol device may be activated prematurely. 20 There is a need for a security system which releases a marking agent in a way on which improves the likelihood of the perpetrator being marked with a marking agent. Throughout this specification reference may be made to documents for the purpose of describing various aspects of the invention. However, no admission is made that any reference cited in this specification constitutes prior art. In particular, it will be 25 understood that the reference to any document herein does not constitute an admission that any of these documents forms part of the common general knowledge in the art in any country. SUMMARY OF THE INVENTION The present invention provides a security system for marking an intruder in an 30 area with a marking agent, the system including: a first sensing circuit for detecting an alarm event associated with the area and enabling a first control signal in response to detecting the alarm event; a reservoir containing a volume of a marking agent; a second sensing circuit for detecting an intrusion into the area and momentarily 35 enabling a second control signal for a predetermined duration in response to detecting the intrusion; and 4 an outlet coupled with the reservoir, the outlet being activatable to release into the area a quantity of the volume of the marking agent from the reservoir when each of the first and the second control signals are enabled. Embodiments of the security system may be used in a variety of different areas. 5 For example, embodiments may be used in any vehicle having an interior area, such as a car, a boat, a caravan, a truck, a van, a train, a tram, a motor-home, an airplane and the like. Embodiments may also be used in any commercial, residential, or industrial premise having an interior area, such as a house, a warehouse, a factory, an office, a shipping container, a laboratory or the like. 10 The marking agent may be any suitable agent which is able to mark an intruder in a way which permits the intruder to be identified as having an "association" with the area. Preferably, the marking agent will comprise a carrier solution and an additive having an identifiable attribute. For example, the carrier solution may include water and the additive may be a polynucleotide composed of any polyribonucleotide or polydeoxribonucleotide. 15 Preferably, the marking agent will be a permanent or semi-permanent marking agent which resists complete removal from the intruder's skin, hair or clothing by conventional chemical or abrasive removal techniques such as techniques involving detergent, alcohol or the like. The marking agent may be visible to the intruder under normal light conditions. 20 Indeed, in some embodiments the marking agent will be a highly visible marking agent. Suitable visible marking agents may include, for example, paint, indelible ink, or a staining agent (such as a food colour). However, in other embodiments the marking agent may not normally be visible to the intruder, but may be visible under certain conditions. For example, in one embodiment the marking agent may include an additive 25 which is visibly responsive to light stimulation. For example, in one embodiment the marking agent includes an additive which is fluorescent under ultraviolet light stimulation. In another embodiment, the marking agent may be visible when viewed with the aid of optical magnification. For example, the marking agent may include microscopic additives which are encoded or labelled with a unique identifier, such as a label or code. When 30 marked with an invisible marking agent the intruder may be unaware that they have been marked and thus may be less likely to attempt to contaminate or remove the marking agent. In an embodiment, the marking agent includes a solution containing one or more identifiable elements such as a trace element, a polynucleotide, or encoded microscopic 35 elements. The identifiable element may be unique to the area. Embodiments which 5 include an identifiable element which is unique to the area may assist in unequivocally identifying an intruder. In embodiments of the present invention that use a marking agent containing a polynucleotide, the polynucleotide may be composed of any polyribonucleotide or 5 polydeoxribonucleotide, which may be unmodified RNA or DNA or modified RNA or DNA. rhe polynucleotide may also contain one or more modified bases or DNA or RNA backbones modified for stability or for other reasons. "Modified" bases include, for example, tritylated bases and unusual bases such as inosine. A variety of modifications 10 can be made to DNA and RNA; thus, "nucleic acid" embraces chemically, enzymatically, or metabolically modified forms. The polynucleotide will provide a known DNA sequence. Methods and techniques for sequencing DNA would well understood. The polynucleotide can be composed of single- and double-stranded DNA, DNA that is a mixture of single- and double-stranded regions, single- and double-stranded 15 RNA, and RNA that is a mixture of single- and double-stranded regions, hybrid molecules comprising DNA and RNA that may be single-stranded or, more typically, double-stranded or a mixture of single- and double-stranded regions. In addition, the polynucleotide can be composed of triple-stranded regions comprising RNA or DNA or both RNA and DNA. 20 Any suitable sensing circuit may be used to detect an intrusion into the area. In an embodiment, the sensing circuit includes one or more sensors, which may be active or passive sensors. Suitable passive sensors may include, for example, infra-red detectors, photodetectors, pressure sensors, temperature sensors, acoustics sensors, electromagnetic sensors, motion sensors (such as a microwave movement sensor), 25 accelerometers, contact switches, or the like. Suitable active sensors may include, for example, a microwave movement detector and optical transmitter/receiver pairs. Of course, other suitable sensors would be known to a skilled person. The first and second sensing circuits may include a single sensor or a sensor network comprising plural sensors of the same or different type. 30 In one embodiment, the second sensing system is an independent sensing system which communicates with the security system of the present invention. The sensing circuit and/or the second sensing system may include interface electronics for interfacing the second sensing system with the security system of the present invention. Irrespective of the type or configuration of the second sensing circuit, the circuit 35 will momentarily enable, or cause to be momentarily enabled, a control signal in response to detecting an intrusion. In this respect, the second sensing circuit may 6 include an output which is controlled by a sensor so as to momentarily enable the control signal when an intrusion is detected by the sensor. In another embodiment, the second sensing circuit controls a switching device, such as a switch, latch or relay, so as to momentarily enable the control signal when an intrusion is detected by the sensor. Thus, 5 in some embodiments the second sensing circuit communicates with a device which momentarily enables the control signal in response to a signal from the sensing circuit. It should be noted that either digital or analogue electronics, or a mixture of these, may be used to implement the sensing circuits. For example, the sensing circuits may include analogue or digital devices, and in the latter case may include software or 10 firmware, for example within a digital signal processor (DSP) chip, a microcontroller, or microprocessor, or other programmed device. Similarly, momentarily enabling the control signal may be achieved using digital or analogue electronics, or a mixture of these. Using a second control signal which is momentarily enabled for a predetermined duration to activate the release a quantity of the marking agent from the reservoir may 15 prevent the entire volume of the reservoir from being released in response to a single detection event, and thus preserves a quantity of the marking agent for a subsequent detection. Thus, a security system in accordance with an embodiment of the present invention may be able to release marking agent for multiple intrusion detection events. In other words, an embodiment may be able to release a quantity of the marking agent into 20 the area for a fixed duration of time for each of plural detection events. In an embodiment, the security system may be configurable and/or programmable to set or adjust the duration, timing, or quantity of the release of the marking agent based on the requirements of the monitored area. For example, in one embodiment the security system furthers including a delay element having an associated 25 delay period which is initiated on detection of the intrusion, so that the second control signal is momentarily enabled on expiry of the delay period. A security system that includes a delay period may provide further flexibility in the system operation for different installations in that the system may be able to be customised for particular installations according to the requirements of that installation. 30 In an embodiment, the security further includes tamper detection circuitry for detecting an unauthorised attempt to disarm the system when armed for intrusion detection. In such an embodiment, and in response to detecting tampering, the outlet is controlled to releases the marking agent. The alarm event may be an event which is triggered by an action of the intruder, 35 which action is not detectable by the second sensor, or which perhaps occurs outside of the area of the vehicle's interior in which the marking agent will be released. Thus, such 7 an embodiment requires the detection of two events before the outlet can be activated to release the marking agent, namely a first alarm event which is detectable by the first sensor, and a detection by the second sensor of the intrusion within the area of the vehicle's interior. Such an embodiment may provide several advantages. First, it may 5 permit the first sensing circuit to be activated by an event which does not place the intruder in the vehicle interior, but which may nevertheless require activation of an alarm signal. Second, the detection of the alarm event by the first sensor may "arm" the security system for releasing the marking agent, but withhold releasing the marking agent until the second sensing circuit has detected the intrusion into the vehicle. In other 10 words, the security system may not be armed to release into the area a quantity of the volume of the marking agent from the reservoir until the first sensing circuit has detected an alarm event. An embodiment which uses a configuration which includes a first and second sensing circuit reduce the vulnerability of the system to counter measure techniques and 15 thus further improve the likelihood of the perpetrator being marked with a marking agent. The present invention also provides a method of marking an intruder in an area with a marking agent, including: providing a reservoir containing a volume of a marking agent; a first sensing circuit detecting an alarm event associated with the area and 20 enabling a first control signal in response to detecting the alarm event; a second sensing circuit detecting an intrusion into the area and momentarily enabling a second control signal for a predetermined duration in response to detecting the intrusion; and activating an outlet coupled with the reservoir to release into the area a quantity 25 of the volume of the marking agent from the reservoir when each of the first and the second control signals are enabled. A particular advantage of the present invention is that it provides a security system which improves the likelihood of the perpetrator being marked with a marking agent. 30 BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in relation to various embodiments of which some aspects are illustrated in the accompanying figures. In the figures: Figure 1 is a block drawing of a security system. 35 Figure 2 is a schematic diagram of a system in accordance with an embodiment of the present invention; and 8 Figure 3 is a partial view of the security system of Fig.2 shown installed in a vehicle. DETAILED DESCRIPTION OF AN EMBODIMENT 5 Before proceeding to describe the present invention, and embodiments thereof, in more detail it is important to note that various terms that will be used throughout the specification have meanings that will be well understood by a skilled addressee. However, for ease of reference, some of these terms will now be defined. The term "enabling" and variants thereof, as used throughout the specification in 10 relation to a signal is to be understood to denote that the state or level of the signal, or signal line, is manipulated or controlled, either directly or indirectly, to convey information. Referring now to Figure 1, there is shown a block diagram of a simple security system 100. In Figure 1, the security system 100 includes a reservoir 102, a sensing 15 circuit 104, and an outlet 106. The reservoir 102 contains a volume of a marking agent 108 for permanently or semi-permanently marking an intruder. In this example the reservoir 102 includes a flexible bag similar to the type used in a windscreen washer kit of a conventional type. However, it will be appreciated that the reservoir 102 may include any suitable storage 20 means and may be flexible or rigid. The marking agent 108 is a fluid composition comprising about 3.5% DNA carrier solution, about 8.5% UV trace solution, and about 88% demineralised water. The DNA contains a polynucleotide having a unique nucleotide sequence. A marking agent 108 that contains a polynucleotide with a nucleotide sequence that is unique to the area "A" 25 is preferred since it permits an intruder marked with the marking agent 108 to be unequivocally identified, once apprehended, using known polynucleotide analytical or forensic techniques, such as nucleic acid sequencing. However, other marking agents 108 may also be used that provide a uniquely identifiable element. The reservoir 102 is coupled to the outlet 106. As illustrated, the outlet 106 30 comprises a hose 107, a pump 110, a one-way valve 112, and a nozzle 114. The pump 110 is integrated with the reservoir 102 so that the pump 110 and the reservoir 102 form a unitary module. In other embodiments the pump 110 may be a separate module, or may not be required. Indeed, it is not essential that a pump 110 be provided since in some embodiments the reservoir 102 may be pressurised, in which case the valve 112, 35 as opposed to the pump 110, may be operated to release the marking agent 108. However, in some applications a non-pressurised reservoir 102 is preferred, in which 9 case a pump 110 is required in order to release the marking agent 108 from the outlet 106. The function of the pump 110, the one-way valve 112 and the nozzle 114 will be described in more detail later. The sensing circuit 104 is configured to detect an intrusion into the area "A" 5 monitored by the system 100 and then to momentarily enable a control signal 116 for a predetermined duration "T" in response to detecting the intrusion, In the present case, the sensing circuit 104 includes is a sensor 105 in the form of a dual zone microwave movement detector. One suitable sensor of this type is the "Dynamco ACC-004" dual zone microwave sensor. It will of course be appreciated that other types of sensors may 10 be used without departing from the invention. In the present case, the sensor 105 directly momentarily enables control signal 116 for a predetermined duration "T" after having sensed movement within the area "A". In the embodiment illustrated in Figure 1, momentarily enabling the control signal 116 involves the sensor 105 momentarily switching the control signal 116 to GND to thus 15 activate the pump 110 to cause a flow of the marking agent 108 to the nozzle 114, via the hose 107 and the valve 112. In other words, the pump 110 is activated for the duration "T". It will of course be appreciated that "enabling" the control signal could be achieved by any suitable signalling scheme and signalling circuitry. For example, although in the present example the control signal 116 is enabled by switching the 20 control signal to GND, enabling the control signal could also involve signalling circuitry which switches the control signal 116 to +V, or that encodes the control signal with information which is decoded to activate the pump 110 As shown in Figure 1, the sensor 105 provides the control signal 116, it will be appreciated that other sensing circuit arrangements will be possible in which the control 25 signal 116 is not provided by the sensor 105, but is nevertheless enabled by the sensor 105. For example, the sensor 105 may provide an output signal which is enabled on sensing an intrusion in the area "A" and which then triggers a timing or delay element (such as a timed relay) to momentarily enable the control signal 116 for a predetermined duration. It will also of course be appreciated that such a delay or timing element may 30 comprise digital or analogue electronics. Irrespective of the configuration or arrangement of the sensing circuit 104, the sensing circuit 104 will either directly or indirectly momentarily enable the control signal 116 for a predetermined duration "T" in response to detecting an intrusion in the area "A". When so enabled, the control signal 116 will cause the outlet 106 to release into the 35 area "A" a quantity of the volume of the marking agent 108 from the reservoir 102.

10 Figure 2 shows a schematic diagram of a system 200 in accordance with an alternative embodiment of the present invention. The embodiment shown in Figure 2 also includes a reservoir 102 for containing a volume of a marking agent 108, a sensing circuit 104 including a sensor 105, and an outlet 106 comprising a valve 112, and a 5 nozzle 114. However, the embodiment illustrated in Figure 2 further includes a switching unit 202 which is responsive to a first control signal (SENSE) from the sensor 105 and a second control signal (ARM) from external electronics to activate release into the area "A" a quantity of the volume of the marking agent 108 from the reservoir 102 when each of the first (SENSE) and the second control (ARM) signals are enabled. 10 In the embodiment illustrated in Figure 2, the switching unit 202 includes a pair of switching devices 204, 206 which are shown here as changeover relays (RELAY A, RELAY B). As shown, a terminal 208 of relay 204 is connected to a +12V power rail and a second terminal 210 of the relay 204 is connected to the ARM signal via a diode 211. In the present case, the ARM signal is a control signal from an external system 15 (not shown) such as an alarm system. However, this is exemplary and it is not essential that the ARM signal be provided by an external system. For example, the ARM signal could be provided by a manual switch which is operable to energise the coil of the relay 204, or it may be provided by a second sensor which is also configured to detect an intrusion within the area "A". In the case of a vehicle installation, a suitable second 20 sensor may include, for example, a sensor to detect shattering of a window, activation of central locking, an occupant in the driver seat. In some installations, such sensors may already be installed in the vehicle as a part of an existing vehicle system, such as a seatbelt monitoring system, central locking system, or the like, and thus may be available for interfacing with a system in accordance with the present invention. 25 When enabled, the ARM signal completes a circuit to GND thus completes a circuit between terminal 210 and GND. Connecting terminal 210 to GND applies +12V across the coil of the relay 204 and closes a switch between the terminals 212, 214 of the relay 204. In other words, whenever the ARM signal is enabled, a circuit is completed between the terminals 212, 214 of the relay 204. Completion of the circuit 30 between the terminals 212, 214 connects the terminal 216 of the second relay 206 to GND and thus energise the coil of that relay 206 by applying +12V across it. Energising the coil of relay 206 completes an electrical circuit between the terminals 220, 222 of the relay 206 and thus connects +12V to the pump 110 and in doing so activates the pump 110 to release a quantity of the volume of the marking 35 agent from the reservoir 102 via the valve 112 and the nozzle 114.

11 As previously explained, because the SENSE control signal is momentarily enabled for a duration "T', the circuit between terminals 212, 214 will only remain completed for the predetermined period. Hence, as soon as the SENSE signal is disabled, the circuit between the terminal 212, 214 will open and isolate the +12V supply 5 from the pump 110. Figure 2 also shows a switch 224 which may be used to manually activate the pump 110, and thus the outlet 106, to release the marking agent. The switch 136 may be, for example, a panic switch which is operable by a user to activate the security system in an emergency situation, such as a car-jacking. 10 Example of System Installation Turning now to Figure 3 there is shown a security system 250 in accordance with an embodiment, as installed in a motor vehicle 300. The system 250 includes a reservoir 102, a sensor 105 (shown here as a microwave movement sensor), a pump 110, a one way valve 112, a nozzle 114, and changeover relays 204, 206, each of which are 15 configured to operate in a similar manner to that described in connection with the system 200 depicted in Figure 2. The system 250, also includes a +12V battery 302, a siren 304 and an panic switch 308 which are electrically interconnected with other electrical components of the system via wiring harness 306. In the embodiment illustrated in Figure 3, the panic 20 switch 308 is operable to provide +12V to pump 110 and thus immediately activate the system 250 to continuously release marking agent 108 until substantially all of the marking agent has been released from the reservoir 102. The valve 112 is located between the reservoir 102 and the nozzle 114 and thus maintains the system 250 in a primed state so that the marking agent 108 is ready for 25 substantially immediate release once the control signal is momentarily enabled by the sensor 105. In this example, the reservoir 102 is fitted behind the glove box of the vehicle. A hose 107 connects the valve 112 to the nozzle 114 which is installed along a the pillar 310, along headline to a front centre position of the interior ceiling of the vehicle 300. 30 Changeover relays 204, 206 are fitted behind driver's side dashboard. The microwave sensor 105 is fitted under centre console proximal to the gear stick and positioned to detect movement through the vehicles front side windows. Once the security system has been "armed", the microwave sensor 105 has an arming period of twenty seconds. Once armed, the microwave sensor 105 will provide a 35 control signal in the form of a three second "pulse" upon detecting an intrusion. In this example, the microwave sensor 105 picks up movement and momentarily enables the 12 control signal 116 (ref. Fig.2) for a predetermined duration "T" of three seconds in response to detecting an intrusion. Thus, in the embodiment illustrated, momentarily enabling the control signal 116 (ref. Fig.2) will not activate the security system 250 to release a quantity of the marking 5 agent 108 unless the siren 304 has been activated by an external alarm system (not shown) or a second sensing circuit (not shown), and thus the system 250 "armed". In other words, in the embodiment illustrated in Figure 3, the marking agent 108 will not be released until the security system 250 has detected movement in the area and, in this example, the siren 304 is sounding. Once both conditions are satisfied, momentarily 10 enabling the control signal will cause the pump 110 to release a quality of the marking agent 108 so as to spray the intruder 312 with the marking agent 108. In addition, whilst the siren 304 is active and further movement is detected inside the vehicle 300, the intruder 312 will continue to be sprayed with three second "pulses" of the marking agent 108. 15 Finally, it will be appreciated that various modifications and variations of the system and methods of the invention described herein will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such 20 specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are apparent to those skilled in the art are intended to be within the scope of the present invention.

Claims (25)

1. A security system for marking an intruder in an area with a marking agent, the system including: 5 a first sensing circuit for detecting an alarm event associated with the area and enabling a first control signal in response to detecting the alarm event; a reservoir containing a volume of a marking agent; a second sensing circuit for detecting an intrusion into the area and momentarily enabling a second control signal for a predetermined duration in 10 response to detecting the intrusion; and an outlet coupled with the reservoir, the outlet being activatable to release into the area a quantity of the volume of the marking agent from the reservoir when each of the first and the second control signals are enabled.

2. A security system according to claim 1 wherein the first sensing circuit detects an 15 alarm event of an external system.

3. A security system according to claim 1 or claim 2 wherein the system is operable to release a quantity of the marking agent into the area for a fixed duration of time each time both the first and second control signals are enabled.

4. A security system according to any one of claims 1 to 3 wherein the second 20 sensing circuit detects motion of the intruder in the area.

5. A system according to any one of claims 1 to 4 wherein the marking agent includes an indelible dye.

6. A system according to any one of claims 1 to 4 wherein the marking agent includes a paint composition. 25

7. A system according to any one of claims 1 to 4 wherein the marking agent includes a fluid containing an indicator agent visibly responsive to light stimulation with incident light having a dominant spectral component in the ultra violet band.

8. A system according to any one of claims 1 to 4 wherein the marking agent 30 includes a fluid containing one or more identifiable elements. 14

9. A system according to claim 8 wherein the one or more identifiable elements include one or more trace elements.

10. A system according to claim 8 wherein the one or more identifiable elements include a polynucleotide. 5

11. A system according to claim 10 wherein the polynucleotide is DNA.

12. A system according to claim 8 wherein the identifiable elements include microscopic elements which are coded or labelled.

13. A system according to any one of claims 8 to 12 wherein the identifiable element is unique to the area. 10

14. A system according to any one of claims 1 to 13 wherein the area is an interior space of a vehicle.

15. A system according to any one of claims 1 to 14 further including a delay element having an associated delay period which is initiated on detection of the intrusion, and wherein the control signal is enabled on expiry of the delay period. 15

16. A system according to any one of claims 1 to 15 further including a control module for controlling the duration of the second control signal.

17. A system according to any one of claims 1 to 16 further including a control module for controlling the timing of the enabling of the second control signal.

18. A system according to any one of claims 1 to 17 further including tamper 20 detection circuitry for detecting tampering to disarm the system when armed for intrusion detection, and wherein in response to detecting tampering the outlet is controlled to releases the marking agent.

19. A security system according to any one of claims 1 to 18 wherein the security system is configurable and/or programmable to set or adjust the duration, timing, 25 or quantity of the release of the marking agent based on the requirements of the area.

20. A method of marking an intruder in an area with a marking agent, including: providing a reservoir containing a volume of a marking agent; 15 a first sensing circuit detecting an alarm event associated with the area and enabling a first control signal in response to detecting the alarm event; a second sensing circuit detecting an intrusion into the area and momentarily enabling a second control signal for a predetermined duration in 5 response to detecting the intrusion; and activating an outlet coupled with the reservoir to release into the area a quantity of the volume of the marking agent from the reservoir when each of the first and the second control signals are enabled. 10

21. A method according to claim 20 wherein the first sensing circuit detects an alarm event of an external system.

22. A security system according to any one of claims 1 to 21 wherein the external system is selected from an alarm system, a panic switch, a seat belt monitoring 15 system, a vehicle central locking system, or a system arranged to interface with the security system.

23. A security system according to any one of the preceding claims further including a pump arranged to pump marking agent from the reservoir to at least one 20 nozzle.

24. A security system according to claim 23 further including a valve between the pump and the at least one nozzle.

25 25. A security system according to claim 24 wherein the valve is a one-way valve.