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Forensic Photography - Analysis, Considerations for Defining a Forensic Photograph and Photographer, Final Words, Organizations

photographs evidence scene court

GALE SPRING
RMIT University

Forensic photography refers to the making of images to record objects, scenes, and events to be used for and within the legal process. Forensic photographs may be taken specifically for documentation, analysis, intelligence, or for court presentations. To be used in court, pictures must be allowed under the rules of evidence that apply in a particular jurisdiction. These rules will indicate whether the images provide information relevant to the court and thus can be admitted as evidence.

Imagery may also be used to extract forensic data such as the measurement of distance, dimension, or location, or to disclose normally invisible detail (e.g., X-ray, infrared, ultraviolet). In the latter cases, the photography may be introduced in court to demonstrate where the data came from, but the resulting testimony associated with the presentation of the images would be more analytical.

Offices of the medical examiner or coroner, police, government agencies, or even insurance companies may employ forensic photographers. Forensic photographers have specific knowledge of the technical nature of photography as well some understanding of laws pertaining to the use of photographs as evidence. However, any photograph may become a “forensic” photograph if it adds information required by the court and can be admitted as evidence.

In all cases, the photograph must be verified with respect to its accuracy and interpretation by the person who created the photograph, a person familiar with the scene or object or by an expert in the field of photographic analysis. This opens up the possibility of experts having a different interpretation of the photograph; however, in the end, all opinions must be supported by a scientific analysis.

Some photographers may offer their services as freelance forensic photographers, while some in the academic community may offer their experience and services to create or interpret images as expert witnesses or consultants. These photographers and experts will have specialist knowledge in areas such as photogrammetry, optics, materials, and processes as well as other technical expertise useful in the interpretation or verification of the authenticity of photographs.

Forensic photographs must demonstrate a fair and accurate representation of the scene, object, situation, or event and be able to be analyzed for information required by the courts. The forensic photographer should be experienced, knowledgeable, and able to anticipate questions that may be asked in an adversarial environment about what the photograph may reveal. These questions may include cross-examination with regard to the accuracy of color, measurements derived from the images, spatial relationships, and the resolution of fine detail; indeed, any point that may undermine or enhance the value of the image as evidence. A qualified forensic photographer will attempt to anticipate these questions and use photographic procedures, protocols, and techniques to cover all contingencies.

Forensic photographs span a wide variety of techniques and use a variety of equipment. Almost anything that will produce an image of forensic relevance, from electron microscope to medical X-ray, is a possible application. The primary motivation that dictates the process is what questions may be asked in court and what is determined to be relevant. The photographer’s knowledge must be wide and cover legal issues from local rules of evidence to an understanding of fundamental ethodology, optics, light, and to a capture material’s performance in certain situations. For thorough forensic analysis, it is not enough to simply take photographs of an object at a crime scene. Forensic photographers should document the scene from several locations and orientations to establish as much objectivity as possible showing any forensically relevant detail within the entire scene. Where possible, scales should be included and measurements and technical camera data and position should be diligently recorded.

A photograph, whether taken for forensic purposes or not, cannot testify for itself; that is, someone must establish its credibility and verify the information of interest in it. The photograph may be made by a forensic photographer, a police photographer, a specialist in photomicrography/photomicrography, or even an amateur at the scene. Images may be taken while an event is occurring, such as a surveillance video, just after the event, or some time later—even years. Similarly, contemporaneous photography of some historical event may be interpreted years later to yield new forensic evidence or insight.

Police photographers primarily take photographs for the police records, documentation, and investigation. Depending on the protocols set out by their agencies, the procedures may be more or less rigorous. Police photographs may be presented in court. These may be in a set taken by the police photographer covering the entire scene or selected photographs. Police photographs should be taken with the same scrutiny as a forensic photograph. They may not be taken with the same thought of future analysis.

Analysis

In analyzing a photograph as evidence, it is important to clearly identify the question that is asked of the photograph. Is it a question of color, detail, spatial relationships, distances, or identification? A photograph may be technically correct in exposure, processing, and printing, but still unable to demonstrate or quantify a specific requirement. For example, black and white photography cannot indicate the color of objects it depicts, unless the spectral sensitivity of the combined detector and filter is known. It may be equally impossible to greatly enlarge an area to gain sufficient detail for an identification of an object or person.

Similarly, precise photogrammetric measurements may not be possible if the original photograph is out of focus or if the focal length of the lens is not known. If there is not enough resolution or sharpness in the original, an enlargement will not reveal additional detail. In fact, enlargement may introduce artifacts that may mislead those not knowledgeable about imaging processes. Finding or identifying a specific point for measurements will be difficult if not impossible and may create varying opinions, thus weakening the use of the image as evidence.

The determination of the size of objects may not be possible without a known scale of size included in the photograph or other technical details noted at the time the photograph was made. Information such as the focal length of the lens and the camera-to-subject distance may prove invaluable in the analysis of the image.

Considerations for Defining a Forensic Photograph and Photographer

Do the photographs tell a complete story? Are they an unbiased, objective approach to the subject or scene? Are they of sufficient quality to be analyzed? Has all the technical data been recorded? Can the photographer explain in court how the photographs were taken and offer assistance in their interpretation? Are post-production methods clearly outlined? This is especially important for digital images.

Forensic photographs should be well-documented as to when and where the photographs were taken, who was the photographer, and what equipment was used. The specific time may be important to add information later if a “reconstruction” is required. The position of the sun and shadows may add additional information about date, time, or season of the year.

In low-light situations where photography is used to reconstruct or demonstrate the event, consideration must be given to the different responses by the human eye and the film, video, or digital capture device, especially with regard to color. The forensic photographer must therefore have more than rudimentary knowledge about how photographic recording differs from visual perception (see Night-Time and Twilight Photography ).

A forensic photographer must be aware of the importance of camera point of view, the created photograph’s perspective. The compression or expansion of perspective through the use of extremely wide angle or telephoto lenses may lead to misinterpretation by a people who do not understand this phenomenon. The relationship between viewpoint and perspective must be fundamental to the working and theoretical knowledge of a forensic photographer.

Zoom lenses are not recommended for forensic applications since their focal length cannot be determined. This can confuse measurements and comparisons of objects in space.

Final Words

Forensic photography is as much a state of mind as a discipline. Forensic imaging is a branch of scientific photography and its practitioners should be guided by strict procedures and protocols and supported by documentation in every aspect of creating the photographs. This includes recording details of equipment/materials, processing and printing information as well as noting time, conditions, distances, scales of size, and the like. Enhanced detail and color may also be questioned in digital and video imaging since much of the processed image comes from interpolation. The concept of the “chain of evidence” is central to forensic photography and is especially true of digital images where their credibility may be questioned due to the ease of manipulation. Ideally, for digital still photography, the original R AW files should be retained as primary evidence in cases likely to be contentious. This approach marks forensic photography as an integral part of scientific imagery.

Organizations

Evidence Photographers International Council (U.S.)
   www.epic-photo.org

Royal Photographic Society, Imaging Science Group (UK)
   www.rps-isg.org

The Institute of Photographic Technology, (Australia)
   www.iptaustralia.com

Biomedical Communications Association (U.S.)
   www.bca.org

Crime Scene and Evidence Photography (U.S.)
   www.crime-scene-investigator.net

International Association for Identification (Scientific Working Group on Imaging Technologies (SWIGT; U.S.)
   http://www.theiai.org/guidelines/swgit/

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