April 3, 2007
Underwater Crime Scene Photography
By Dutelle, Aric
Today's forensic photographer is well versed in the methodology and logistics associated with abovewater photography. There has been a great deal of emphasis and training dedicated to ensuring that proper viewing angles, distances and subject matter are captured in an effort to record a true and accurate depiction of the scene as it was when the photographer shot it. However, what if the crime scene in question was located under water? Would the same practices and methodologies apply? Would the same equipment and personnel be appropriate?Environmental challenges require both personnel and equipment modifications in order to effectively document an underwater crime scene. How does depth affect color? How does the density of water affect subject size and clarity? How do the photographer and the equipment compensate for such difficulties? What are the processing methodologies and both equipment and training issues?
Oftentimes, the SOPs associated with processing crime scenes are forgotten or ignored when encountered with an underwater crime scene. There are many reasons for this occurring, some of which include equipment, manpower, and/or environmental issues. More often, it is a result of improperly trained or equipped personnel or a case of rushing and thinking, "It won't really matter as long as we get the stuff." However, the underwater scene and its contents are equally important and subject to the same scrutiny and legal considerations as a land-based scene and should therefore be processed in an equally thorough and competent manner.
The first obvious hurdle is that typically an underwater scene will require the photographer to submerge him or herself in order that the scene be documented. This usually requires that the photographer be a certified diver in order to effectively document an in-water event. With an exception being very shallow water photography, accomplished by either wading or taking photographs from a boat or other floating object, the individual tasked with the duty must be a competent swimmer and underwater diver, as well as a skilled photographer.
Whenever a person enters an environment within which his body was not meant to live, there are hazards, risks, and restrictions involved. The person assigned the duty of underwater photography must be both physically and mentally capable of venturing into and working within the underwater environment.
There are several organizations that will certify a person as a diver. Some are dedicated to recreational divers and a more civilian concentrated population (PADI, NAUI, SSI, etc.), and others are specifically related to public safety professionals (Dive Rescue International, Miami-Dade). Each has a purpose and a niche, however, the important matter is that an underwater photographer be certified, comfortable, and competent in order that he can effectively perform his assigned duties.
The Underwater Environment
In addition to training regarding how an in-water scene affects the human body, the individual also must be trained with regards to how the underwater environment affects photography. It is not enough to be a skilled top-side photographer and think that one will be equally successful employing that knowledge and technique sublevel. There are several issues that must be addressed in order to effectively and accurately capture the underwater crime scene.
The first obstacle is equipment. A photographer is not typically able to employ the same photographic equipment that he uses for land- based crime scenes. Special marine or underwater cameras must be used or underwater housings used to encapsulate the equipment. This requires the photographer to have a working knowledge of the use and maintenance of such equipment. However, having the correct equipment is not enough. The photographer must next overcome the difficult environmental issues involved with underwater photography.
The first major environmental issue encountered by the underwater photographer is distortion. Water refracts light rays differently below the surface of the water. Unlike above the water, underwater light refraction causes objects to be magnified. For this reason, images and distances are distorted. In fact, objects underwater will appear about 33% larger. Thus, it is extremely important to include a scaled object for reference. Although the scale will also be magnified, it will be magnified in direct relation to the object in question, thereby enabling a viewer to interpret the true size and dimension of the subject matter.
Another major problem is subject coloration. As depth increases, light rays of red, orange, and yellow are filtered out by the water. Eventually, the diver is left with only blue and green rays. Even in the clearest of waters, only blue and green wavelengths typically penetrate at a depth of more than 30 feet. This depth is significantly reduced if the water is polluted or murky. One way in which the photographer can overcome this loss of color is to shoot the photograph facing upward toward the surface, thereby using the most natural light penetration available.
Because natural light is quickly absorbed or scattered by water, artificial light is often essential. The addition of a strobe, thereby adding electronic flash lighting to the scene, is useful for two reasons: to illuminate the subject matter, and to obtain the true color of underwater objects and surroundings. However, water is significantly more dense than air, and electronic flash will not typically penetrate or light objects further away than 6 to 8 feet, depending on the strength of the strobe employed.
Color correction (or compensation) filters can be attached to the lens in instances where overall photos are being taken. A strobe, however, must not be used for this, as it will not provide the correct coloration. Color correction filters are designed to be used without the strobe. If a color correction filter is used, it must be reflected on a diver's photo log. Remember, the important thing about crime scene photography is that it is a true and accurate portrayal of the scene as it was when the photograph was taken.
Technically, the scene was viewed by the photographer in unnatural colors of shades of green and blue, not in the "true" colors compensated for by the filter. However, the filter does make the photo more realistic as to what the subject matter would or should look like were it not for the environmental abnormalities associated with being underwater.
In addition to distortion, coloration and lighting issues, many times the environment itself will create difficulty for the underwater photographer. Silt, sediment, algae and pollution can create what are called "black" or "brown" diving conditions. These are conditions where visibility can be less than 1 or 2 feet. It is especially important for the photographer to have good diving skills to ensure proper buoyancy so as not to disturb the environment and affect photo quality.
Adapting to Underwater
To overcome the difficulties encountered when photographing an underwater scene, there are a few basic methods to employ. If possible, stay shallow. This will reduce the color loss from light reaching the subject matter. However, if the crime scene is deep and photographs must be taken at a greater depth, the use of a strobe or color correction filter must be employed.
Whenever possible, use a strobe (electronic flash). This will replace the light that is lost underwater. Again, the only time when it is not suggested that a strobe be employed is when the photographer is making use of a color correction filter for overall photos taken at depth.
Stay close to your subject. Because of underwater distortion, coloration issues, and environmental haze, it is wise to keep the distance between the subject and camera as close as possible.
Maintain proper buoyancy. If a diver-photographer is able to maintain his proper altitude, it will reduce or eliminate distortion and obliteration caused by stirring up environmental elements.
Processing the Underwater Scene
When confronted with an underwater crime scene, the investigation team must take into account that there are multiple scenes and levels that must be accounted for. Just as in an above-water scene, there will need to be multiple methods of documentation that must occur. These remain the same. They are typically: still photography, videography, sketching/mapping, and the written report.
When documenting the scene through these four methods, the investigation team must remember that there are two types of scenes that must be documented. The first is the surface scene. This includes any water access points such as piers, shorelines or waterfronts, as well as the surface of the water. All of the aforementioned must be thoroughly searched, photographed and located items of evidence noted on a sketch.
The other type of scene is the submerged scene. The submerged scene has the added difficulty of depth, as well as the aforementioned environmental issues and visibility issues, which compound the problem. This is why it is imperative that only those people who have received proper training and certification in such matters be utilized to conduct underwater search-and-recovery operations.
The submerged scene includes the objects located at depth, as we\ll as the level at which they were found. It is a three- dimensional scene, often with very little in the way of fixed markers or items to aid in reference. Just as with the surface scene, this area must be thoroughly searched. Items of evidence must be photographed, marked and their positions and depths noted on a sketch. It is suggested that the diver or dive team assemble a diver's slate made specifically for the purpose of annotating underwater scene information.
Just as with the surface scene, items of evidence must be properly located, documented, collected and preserved. Items of evidence recovered from water will require special handling and packaging. Depending on the item, sometimes it is suggested to package the item underwater, thereby ensuring the collection of any trace material adhering to the item.
It is often suggested that the item be packaged in the water in which it was found to slow environmental deterioration possibly caused by removing the item from water. As was mentioned before, it is extremely important that an individual familiar with the collection and preservation of underwater evidence be used for such matters.
All too often, underwater crime scenes-and the evidence collected- are not properly documented or processed. This failure can result in a loss, contamination or inadmissibility of the evidence. Proper underwater crime scene processing and documentation methods will ensure that the evidence is located, properly documented, preserved, and able to be used in subsequent litigation.
It is important that the underwater investigation team be properly trained and take part in ongoing training specifically relating to matters of crime-scene documentation and processing methods involving the underwater environment. What is not searched for will not be found. What is not found cannot be analyzed to uncover the truth.
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Aric Dutelle is a professor of forensic investigation at the University of Wisconsin-Platteville. He is also a sheriffs patrol deputy for the Grant County, WI Sheriff's Office and is a certified dive master and underwater photographer. He can be reached at [email protected]
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