Photographing Footwear Evidence
Written by Dwane Hilderbrand   

Taking quality examination photographs

When making quality examination photographs of the evidence prints, be sure to use the same numbered marker you used when you were showing the relationship of the print to the scene. In order for a footwear examiner to perform a quality examination, high-quality, close-up photographs are required. Since footwear evidence can come in two different forms—prints and impres-sions—the techniques of photography are slightly different. This can be easily obtained with a little time and patience. There are many types of cameras that are being used for crime-scene photo-graphy, ranging from 35 mm and 4 x 5 film cameras to digital cameras.

After the selection of the camera and the film or digital media, you will need to select an appropriate scale that will be present in all the photographs. This is very critical in order to allow for enlargement from the negative or image to make an exact duplicate of size (1:1). When no scale is utilized in the photograph, the examiner has no idea what the size of the real impression is. It then becomes difficult for the forensic photographer to print 1:1 scale photographs for examination purposes.

The scale should be at least 12 in. (300 mm) in length, but smaller scales can be used. In some cases where a ruler is not available, other measuring devices can be used—such as a business card—as long as the crime-scene investigator remembers to submit the measuring device that was used, along with the negatives, in order that it may be used as a standard in preparing the 1:1 photographs.

The scale needs to be placed on the same plane as the impression. Why? Because even a difference of 1/2 in. in depth may cause size discrepancies that become a factor when comparing the image to a suspect’s shoes.
(Just a quick note: In footwear, the shoe sizes vary by an increment of 1/3 in. for length; half sizes vary by 1/6 in. In other words, a Size 9 is 1/3 in. shorter than a Size 10. As you can see, there is not much room for error when placing the scale on the proper plane with the impression.)

Here is another helpful idea:

You can use a golfball marker or a thumbtack as a simple device to assist in showing the direction and height of the flash. The golfball marker or thumb-tack is placed in the photograph along with the scale and an information card. By turning the golfball marker or thumbtack upside down, with the point upwards, a shadow line will be produced when the photograph is taken, showing the light direction. You can then measure this line and the height of the golfball marker. By doing this you can achieve two of the three sides of a triangle; the third side of the triangle can then be determined quickly by using simple mathematics. Once this has been determined, the angle at which the crime-scene investigator stood when the photograph was taken can now be reproduced, if necessary. This will be necessary in some cases where the foot-wear examiner needs to cause the same shadowing effect in the test impressions as were shown in the crime-scene photographs.

Photographic procedures for three-dimensional impressions

The camera is mounted on a tripod and rotated in such a manner that the plane of the film is parallel to the plane of the print. This will enable you to print a 1:1 scale photograph of the footwear impression for comparison. The print, the scale, a small golfball marker, and an information card should fill the frame of the finished photograph.

When using a flash, the flash should be held at least at a 45-degree angle from the print and fired from three different positions with at least 100 degrees of separation. By using this oblique lighting procedure, a different amount of light can be reflected from the shadowed and non-shadowed areas, thus providing greater contrast.

This footwear impression was photographed in what might seem at first to be the logical manner: Hold the camera and the flash directly above the print and shoot the photograph. The above photograph shows the result. You can make out the size and the design—but the details leave something to be desired. Now look at the photo on the next page.

This oblique lighting will cause a greater amount of contrast so detail can be obtained in the photograph. The best way to do this is to fire the flash at the three different positions of the tripod legs making sure not to get the legs of the tripod in the way of the flash. A minimum of four photographs is taken for each shoeprint when using a flash: one without a scale and three with the scale. And a minimum of three photo-graphs is taken for each shoeprint when not using a flash: one without the scale and two with the scale. But remember, the best-quality impressions are those impressions taken with a flash, since the flash will create “false” shadows. The scale should always be placed parallel to the side of the impression, never in the impression itself. If the impression or the print is located in a brightly lit area (outside in direct sunlight, for example), a “false-shadow” effect may need to be created in order to obtain the best-quality photograph possible. Creating a shadow to fall over the entire impression or print and then using the flash as your light source can easily achieve this effect.

You should never photograph foot-wear impressions in soil, sand, or snow using direct sunlight as your light source, because you cannot control the shadows that the sun will create.

If the impression is located in very deep soil, the flash should be held slightly higher to avoid casting a shadow over part of the impression. Those impressions that are located in foreign substances under the existing light—but are not further enhanced with the oblique-lighting technique—will need to be photographed using existing light. When using existing light on reflective surfaces, the camera’s light meter receives incorrect readings from the surface and in turn gives an incorrect meter reading. In most cases, the lens opening of the camera should be set at least one to two stops smaller than the meter reading to reduce the amount of light. In other words, if the meter reading says f11, the camera should be set to f16 or f22. In any case, it is advisable to take several photographs of the impressions—and remember to bracket the exposures.

This is the very same footwear impression that appears on the previous page. But in this example, the photographer has caused a shadow to fall over the impression. He then used a flash located to one side of the print to create a “false-shadow” effect that served to bring out the maximum amount of detail that was present in the print.

If the footwear evidence is an imprint, the same procedures should always be followed. The direction of the camera may change, but the plane of the camera’s film should still be parallel to the surface of the imprint. Sometimes the evidence can be located in the oddest positions and places.

The crime scene investigator should also remember that it is your initiative that helps in the photographing of this type of evidence when they are in these odd positions or places.

Photographic procedure for certain two-dimensional impressions

When photographing footwear imprints in dust, you should mount the camera in the same manner as you would for three-dimensional impressions or prints. The only change in the actual photography is the position of the flash.

With prints in dust, the flash should be placed so the light skims along the surface of the impression. Using a flashlight will help you in determining the exact location where you should place the flash. Hold the flash at least three to four feet from the imprint on the same plane and fire it at three different positions, making sure to get at least a 100-degree separation between the shots. Once again, you can use the three openings between the tripod legs. By placing the flash on the same plane as the imprint, the oblique light is more effective in obtaining the detail that is needed. This procedure causes the light to be reflected off of the dust or residue particles and up into the camera lens.

To more clearly explain this particular procedure, consider how you might want to approach two entirely different cases:

  • In the first case, the unknown footwear impression is located in a room with lighting coming in from all angles. In order to properly photograph this imprint, all of the excess lighting needs to be blocked out so that the photographer can obtain good control of the lighting.
  • In the second case, the unknown footwear impression or print is located on top of a stainless-steel sink, which will cause a substantial amount of reflection of the ambient light. Once again, the ambient light needs to be blocked out so the photographer can get control of the lighting and achieve a good photograph of the print.

The crime-scene investigator in most cases will need to open the aperture three to four stops more than what the dial on the flash indicates. And once again you are advised to remember that bracketing exposures using several different apertures is a highly recommended procedure.

About the Author

Dwane Hilderbrand is a senior consultant and instructor with Ron Smith & Assoc-iates, Inc. His career has included 24 years of service with the Scottsdale (Arizona) Police Department. He is one of the few forensic professionals in the world who has earned certifications from the International Association for Identification (IAI) for Certified Latent Print Examiner; Certified Senior Crime Scene Analyst; and Certified Footwear Examiner.

 


ORIGINALLY PUBLISHED:
"Photographing Footwear Evidence," written by Dwane Hilderbrand
March-April 2008 (Volume 6, Number 2)
Evidence Technology Magazine
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