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Police Photography

camera digital evidence cameras

LARRY S. MILLER
East Tennessee State University

The first known use of the camera for law enforcement purposes was in the mid 19th century, initially to record still images of arrested individuals and to document crime scenes. This is still important today, but police also now use camera and video to record interrogations, traffic stops, surveillance, public thoroughfares, and traffic accidents. They also frequently use cameras to document physical evidence at a crime scene before it is collected into evidence. Fingerprints developed with fluorescent powder or illuminated by an alternate light source (ALS, an intense light source with filters capable of illuminating a wide range of wavelengths from the short-wave ultraviolet (230nm) through the near infrared (900nm), commonly used to search for trace evidence at a crime scene) is an example of this. The police photographer must have an understanding of how the camera can record not only the visual and audio components of an interrogation or traffic stop but also how it can record images at invisible ultraviolet (UV) and infrared (IR) wavelengths. The police photographer must also have a good working knowledge of other specialized techniques such as close-up (macro) photographs, the effective use of fill-flash and bounce flash, and photography in less than desirable conditions such as night-time with limited ambient lighting.

Most police agencies use a hybrid system for their photographic needs. This hybrid system is composed of a digital camera, a 35 mm single lens reflex (SLR) camera, and a video camcorder. When the digital camera emerged in the late 20th century, it was touted as the replacement for traditional film cameras. This proved not to be true, at least into the early 21st century. Nonetheless, digital cameras are very useful in police photography. They are able to capture images in the invisible range, particularly in the IR. Other advantages of digital cameras include the ability of the photographer to see the immediate results of the photo, the ability to send digital photos over the internet and to computer-equipped police cars, the ability to record images over a wide range of the spectrum from the UV into the IR, and storage capability. However, digital cameras may not perform well in low light situations, when enlargements of greater than about 24 × 36 cm (11 × 14 inches) are required, or when a crime scene must be recorded at night using a painting-with-light technique. In these situations a film camera should be used. A 12 megabyte digital camera might be able to produce an acceptable 24 × 36 cm enlargement, but the cost of such a camera may be prohibitive for a police department. As a result, most law enforcement agencies use the same make of digital camera as their film camera in order to use the same accessories. For instance, if a police agency uses a Nikon 35 mm SLR camera then the digital camera is going to be a Nikon SLR so that the same lenses, filters, flashes, etc., can be used for both cameras. In this way, the department does not have to invest in different accessories to fit each camera. An exception to this is the video camcorder, which typically uses different lenses and filters.

The major function of the police photographer is to document crime scenes and injuries that may be used as evidence in court. Any photograph or video used as evidence in court must be admitted into evidence based on the rules of evidence. The photographer must be able to testify that a photograph or video accurately represents the scene or the victim, and that the photograph was not altered or manipulated in any way to distort the scene or injuries. This has been a particularly difficult task with digital photographs which can be easily altered. However, most departments have strict protocols when using digital images and typically archive images as RAW files to maintain integrity of the original. Photographs admitted into evidence must be relevant and not intended to bias the jury. Photographs of deceased or injured individuals may be objected to on the basis of how shocking the photographs are to a jury. Unless a particularly gruesome photograph can be shown to be relevant to the facts of the case, it may not be admitted into evidence. One exception to this rule is during sentencing hearings, where the prosecution wants to show a jury how heinous a particular crime was. A general rule for police photographers is to tell a story with the photographs. For crime scenes, this means showing surrounding areas, entrances and exits to the scene, articles of evidence in their original locations and close-ups of that evidence, as well as the physical environment (i.e., was food on a table, dishes in a sink, property disturbed, etc.). This helps the jury understand the context and what was going on at the time of the crime.

To document crime scenes and injuries, the police photographer may have to use specialized photographic techniques. Close-up or macro photography is used to focus closely on a specific item of evidence (i.e., fingerprints, shell casings, bullet holes, footprints and tire prints, etc.). Either a digital SLR camera or a 35 mm SLR camera fitted with a macro-capable lens will usually be suitable. Years ago, special fingerprint cameras were used that were based on 4 × 5 film Graflex cameras or Polaroid equipment. Today, a macro lens and SLR camera is generally preferred by most professional police photographers. Documenting the location of invisible evidence is also a specialized photographic task. UV and IR light sources extending to 230nm in the UV and to 900nm in the IR are often used to locate trace evidence that might not be seen readily by the naked eye under normal lighting conditions (i.e., fluorescent fingerprints, blood, semen, fibers, hair, dust, gunpowder residues, etc.). Of course, the camera and its detector must be able to record images in these widely differing wavelengths. The digital camera is especially well suited to this type of photography. The CCD or CMOS chip that records the image in a digital camera is sensitive to these wavelengths and can record images with ultraviolet or infrared illumination only with appropriate filtration. Conventional film, while sensitive to UV, is not particularly useful for IR wavelengths so a special infrared film must be used in this case. UV and IR light can also reveal bruises, bite marks, and other injures long after they have faded, even tattoos on a decomposed body may be detected.

While photographing light at invisible wavelengths is a useful way of revealing the unseen, visible light remains a very versatile medium. One method often used at night time or in unlit interiors is painting-with-light. With this technique, the camera is on a tripod or other firm support and the f-stop value at f/22 or higher. With the shutter open the photographer fires a series of electronic flashes at various points in the scene (see Cave Photography ). In this way, one photograph captures the scene as though it was lit with simultaneous multiple flashes (see Figures 89 and 90). Film cameras are best suited for this technique since digital cameras produce noise with long exposures. However, with digital cameras the same technique can be emulated by using multiple flash units with one or more slave attachments. Other light-directing techniques the police photographer may use are fill-flash, bounce flash, and grazing. Grazing incidence (low angle) light allows the photographer to capture shadow details in low profile footprints or tire prints. A scale, such as a ruler, must be placed in these types of photographs so that, if a suspect’s shoe or tire is recovered, it can be compared to the photograph.

The police photographer may be called upon to assist with surveillance photography, often employing both still images taken with a digital or 35 mm SLR camera, and movies with a video camcorder. Surveillance photographs can document a crime in the act of commission and may provide evidence for a search warrant. They may also identify arson suspects or capture images of suspected individuals in public areas for terrorist investigations. Regardless of the case, the photographer must be able to capture the identities of people and location in the photograph or video. Facial and body features, unambiguous location identifiers with street addresses, car tags, and the like must be visible in the recorded images. In most cases, police surveillance photography is covert, requiring that the photographer and the camera be hidden from view. Thus the use of telephoto lenses and high-speed film for low light conditions may be required. There are several 35mm films available with speeds of ISO 3200 and higher that can be used for this purpose. Also, some digital cameras and camcorders are capable of high-speed recording and infrared illumination recording using the nightshot feature on many digital cameras.

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over 2 years ago

ramu sir certive good

dirctor.

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almost 3 years ago

I really enjoy reading your posts. I use them a lot for school and it helps out a lot. Thanks and keep up the good work.

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about 3 years ago

thank you this articles is very help us.

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over 3 years ago

stick to the basic principle of police photography whereas learner will not be confused. much more needed are those research materials in forensic photography.

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almost 4 years ago

it's very useful for me as a professor but perhaps it's not only me who would harvest its importance and usefullness most likely to students who are conducting research in this field