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Surveillance Technology: An End to Stakeouts?

Modern surveillance techniques still use the old methods, but technology can make the process both easier and more likely to yield good results.

Tim Dees Headshot

The stakeout is an honored police tradition, and the setting for any number of television and movie scenes. Stakeouts most quickly come to mind when cops talk about surveillance, and most stakeouts are pretty low-tech. A pair of binoculars, a car or van, and a steady supply of bad coffee is all the hero requires to get his (or her) man.

Of course, in the movies, the bad guy never goes out the back door, is always immediately recognizable from everyone else in the neighborhood, and well-intentioned patrol cops don't notice the suspicious person watching the premises. Also no one ever has to go to the bathroom, and the word "hinky" will be used at least once.

Modern surveillance techniques still use the old methods, but technology can make the process both easier and more likely to yield good results. Sometimes it's not necessary to keep a watcher on site at all. Fixed surveillance video cameras never get sleepy, and video analytics software can help separate the interesting parts of the recording from the hours where nothing moves. The most significant problem with cameras isn't technical, though. It's finding someplace to put them.

Location, Location, Location

In a high-crime area, a permanent or semi-permanent camera on a utility pole or other support may deter the bad guys, but it's not often you have a great mount point right where and when you need it. This problem isn't restricted to local law enforcement.

The U.S. Border Patrol is often hampered by land use rules when they need to shift surveillance to a newly active border segment. Even when the land where the surveillance is needed is under federal control, the USBP doesn't necessarily have the clearance to move their equipment in. Much of the frontier is managed by the Departments of the Interior or Agriculture, and by the time their bureaucracies have reviewed the request and determined there is no adverse environmental, cultural, or historical impact, the border activity has shifted and the surveillance there is no longer valuable.

The surveillance system itself may become a crime target. Cameras and their associated hardware are prime vandalism and theft targets. The cameras generally point in a single direction. If the thief approaches from another area, he's free to take his time removing and/or destroying the camera. This was a story line in the cable series "The Wire." A detective placed an expensive wireless surveillance camera at what he thought was a hidden location. The camera was stolen, and he had to compromise himself to get it back and avoid heat from his superiors.

The automated license place recognition (ALPR) systems that are so popular right now are another form of surveillance technology. These systems are best known for identifying stolen vehicles, scofflaws, and other license plates of interest contained in their onboard databases. But used passively, they can simply record every license plate that comes in view of their cameras, noting the time and place of the recording. This data can be analyzed later to establish or confirm alibis and place suspect vehicles in the area of a crime, even though the crime was unknown at the time the record was made.


Moving surveillances, where the desired information is in where the target is and is going, is a combination of art and science. When traffic is light and the target is unsuspecting, it's easy to pull off. If the target is skilled in counter-surveillance, traffic is dense, or you don't have enough people and vehicles, it's a huge headache. Global positioning satellite (GPS) technology isn't new, but advances in the size, endurance, and cost of the hardware make it an attractive alternative to the traditional "tail."[PAGEBREAK]

If your crook is accommodating enough to carry a cell phone you can track, you don't have to be concerned about hardware, but you do have to secure a search warrant with the cellular service provider and be dependent on its network for the information. Dedicated GPS recorders and transmitters are a surer bet here.

GPS surveillance devices fall into two major categories: active and passive. The active devices transmit their locations (as well as speed and direction of travel) in real time, so you know where the device is at any given moment.

The chief limiter of these gadgets is power. It requires quite a bit of current to transmit continuously, and few of them have batteries that will last more than a day or two. A subset of these preserves battery power by transmitting a text message at pre-programmed intervals, giving the location coordinates from the GPS receiver.

Passive devices merely record their travels in internal memory. When you retrieve the device, you dump the memory to see when and where it's been. These are considerably cheaper than the active devices, and their batteries can run for a week or more before going dry.

New research at The University of Memphis gives rise to new technology that largely defeats the battery/power problem. AutoWitness is a penny-sized device intended for concealment inside theft-prone items like computers. A motion-detecting accelerometer, gyroscope, and vibration sensors on the AutoWitness determine when the object is being moved, and whether the movement is characteristic of everyday activities or something new, indicating theft. The sensors also pick up on direction of movement, serving as a kind of dead reckoning positioning system.

The movements are logged internally until a pre-programmed interval has passed (so as to avoid detection) and the AutoWitness senses that there is a sufficiently strong cellular network or other RF signal suitable for transmitting its data. It works best when it is surrounded by a dedicated network of base stations intended to detect the devices and receive their transmissions. However, location detection is about 90 percent accurate when the only localization data is from cell towers. When it comes time to find the specific location of the item carrying the AutoWitness, a dedicated handheld receiver can interrogate and locate the device.

AutoWitness has the potential for some interesting moving surveillance applications. One of the most attractive aspects of this technology (which is truly remarkable and far too complex for me to address here) is that the finished product is expected to cost only $10-$20 per unit.

Seeing Inside

Sometimes your eyes are not enough. If you need to know what's inside a car, package, or other container, you either need to search it by hand or use some tool to make that unnecessary. The latest and greatest tech in this area is backscatter (as opposed to transmitted) X-ray.

Traditional X-ray images are transmitted. The X-rays pass through the imaged object, which absorbs some of the energy. The rest falls onto a sensor or X-ray film, which displays a shadow in areas of less density and light areas to represent greater density.[PAGEBREAK]

Backscatter X-ray works from reflected, or scattered, X-ray energy, so there's no need for a film or sensor on the opposite side of the imaged object. Objects composed of elements with low atomic numbers scatter more energy than the ones made from relatively high atomic number items. All organic compounds, including drugs, explosives, and people, contain carbon (atomic number=6), oxygen (8), hydrogen (1), and so on. Steel is mostly iron (atomic number=26).

At airport security checkpoints, backscatter X-ray devices are in use to detect things a metal detector can miss. Most anything that doesn't fit the characteristic signature of clothing or tissue will be readily apparent on the backscatter display. On a larger scale, backscatter X-ray scanners can "see" through vehicles and cargo containers to reveal concealed people, drugs, and other possible contraband. The vehicle-size scanners fit into a van.

American Science and Engineering (AS&E), the largest manufacturer of backscatter X-ray devices, has sold at least 400 Z Backscatter Vans or ZBVs, but the company won't say who it sold them to. The U.S. Customs and Border Protection (CBP) agency has some of them.

X-rays are ionizing radiation, and are potentially harmful to human tissue. Exposure to radiation is an understandable concern for people who may or may not be aware they are being subjected to this kind of surveillance. It's evident enough at the TSA checkpoint, but possibly not so obvious when a vehicle-size scanner is in use. AS&E maintains that a typical scan involves about the same amount of radiation exposure as one would receive in two minutes of flying in a commercial airliner at cruise altitude (cosmic radiation increases as the atmosphere gets thinner).

Privacy Concerns

Exposure to radiation isn't the only aspect of surveillance John Q. Public is worried about. No one likes to be watched, and the perception that the police are always watching you creates an aura of oppression, not safety. New police technologies usually give rise to new case law, but the rules of the game haven't changed all that much.

The legality of any police surveillance is governed by the Fourth Amendment, and whether there has been a search, usually defined as "an intrusion into a reasonable expectation of privacy." So long as the police are in a place they're allowed to be, and seeing what anyone can see with their own eyes, there's no expectation of privacy.

Use of GPS monitoring devices, even when they have been placed on vehicles surreptitiously, is not a search, or so says the 7th Circuit in U.S. v. Garcia. In this case, Garcia was a predicate felon for dealing in methamphetamine, and an informant told the police he was distributing it and planned to start manufacturing it.

Police placed a passive GPS device on Garcia's vehicle (presumably while the car was in a public place, as there was no trespass claim) and found it had traveled to a parcel of land. The police obtained a search warrant for the land, found Garcia's meth lab, and arrested him when he returned to it. Garcia tried to suppress the information from the tracking device, but the court said the device didn't provide them any information they couldn't have gained from a conventional surveillance.

The same rationale applies to ALPR data. An ALPR is essentially a cop with a good eye and really fast note-taking skills. It doesn't capture anything a patrol officer couldn't see with his or her own eyes.

X-ray devices are another matter, of course, since only Superman can see inside a vehicle without a physical intrusion. So far, these machines are used only where suspicionless searches are lawful, like TSA checkpoints and border crossings, so there are no Fourth Amendment issues-not that people don't try to raise them. The airport backscatter machines produce an image that some people feel is too close to nudity, as it shows anatomical details concealed by clothing. The remedy is to request a hand search, which most people don't like much, either. 

So, make it easy on yourself and use the surveillance tech that's available to you. Maybe the next generation of technology will address the problem of where all that coffee consumed on stakeouts is supposed to go. 

Tim Dees is a retired police officer and the former editor of two major law enforcement Websites who writes and consults on technology applications in criminal justice. He can be reached via

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Officer (Ret.)
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