Video cameras aren't used just to document crime scenes. Many agencies utilize video cameras in patrol cars, especially traffic and DUI units. Video can be used in court to show that standard field sobriety tests were administered properly and why the driver failed the roadside maneuvers.

Interview and interrogation rooms at police departments are often set up with covert video and audio. The advantage of a covert installation is that oftentimes suspects, victims, and witnesses are less likely to speak openly if they are aware that the interview is recorded.

Pinhole cameras can be purchased for as little as $25. These cameras are very small and concealable. The video quality is good, but because the optics are so small—not much bigger than the diameter of a pin—the lenses suffer from some amount of distortion.

The camera can be installed in a false thermostat or any other object likely to be on a wall. The video output is run to a separate location where monitors and recording equipment are located.

Other detectives, prosecutors, and even defense attorneys can watch the interview in real time. The benefits are large and the cost is small to set up an interview room with covert video.

Another option is a pinhole camera and wireless transmitter. Camera/transmitter combinations are available concealed in common household items such as alarm clocks, portable radios, wall-mounted clocks, and smoke detectors. The video signal is transmitted to a receiver located at a remote location. The video receiver is connected to a video recording device, such as a VHS or Hi8 VCR or even into the analog inputs on a digital camcorder.

The primary advantage is that the video is transmitted over the airwaves so no wires need to be installed between the camera and the recording device. The range of these 2.4-gigahertz FM systems is at least a few hundred feet and can be extended to about half a mile with additional antennas. The cost is low, starting at about $300 for the camera, transmitter, and receiver.

Longer ranges—often a number of miles—can be achieved, but the cost is around $3,000. In situations where wireless video is not practical, a small video camera can be connected to a miniature Hi8 or Digital8 recorder.

The recorder is placed in a backpack or fanny pack and the camera is secreted on the undercover officer. This rig is great for monitoring and recording protests or other mass demonstrations because it allows for freedom of movement and has no distance restrictions. Cameras can also be installed in remote locations where video would greatly increase the chance of apprehending the suspect, such as a residence that is repeatedly burglarized.

This self-contained installation can include any type of small video camera, such as a wireless alarm clock or a wired micro camera concealed anywhere within the room. The video signal is transmitted or run to a device called a VMD or video motion detector.

The VMD is connected to a recording device such as an Exxis Spycorder, a special VCR that connects to a VMD. The VMD triggers the VCR to record when the camera detects movement. The operator can identify up to four areas in the image where movement is likely to occur, such as a hallway or window, or simply along the left and right side of the image frame.

When an object moves across the highlighted areas, the VMD tells the VCR to record the scene for a specified number of minutes. The advantage is that one tape can last for weeks in a low traffic area, because the unit does not record continuously.

A VMD starts at about $200 and a Spycorder VCR is about $300.