Domestic Violence Photography
Lt. James O. Pex
Oregon State Police
Coos Bay Forensic Laboratory
Documentation by photography is an important and powerful tool in the
investigation of domestic violence crimes. When injuries resulting from domestic
violence are promptly and adequately documented, it is possible for prosecution
to occur without the victim's testimony.
Often, victims of domestic violence are dependent upon the abuser for food
and shelter. If the abuser is only jailed temporarily after the initial arrest,
it is possible for an abuser to coerce the victim into not testifying. Therefore,
the importance of documentation becomes relevant in preventing the recurring
abuse of victims. The pictures can be used in the event that the victim later
becomes unwilling to testify.
The objective this article is to provide some basic knowledge of photography
and illustrate four photographic techniques that have proven to be successful
in domestic violence cases: color photography, alternative light source (narrow
band light source) photography, reflective ultraviolet (UV) photography,
and infrared (IR) photography. In addition, affordability of the necessary
equipment is a concern, and the illustrated techniques were developed with
this in mind.
The colors that are visible to the eye represent only a small portion of
the light spectrum, also known as the electromagnetic spectrum. Visible light,
or white light, is a combination of all the visible colors. A beam of white
light can be separated into the visible spectrum using a prism. The band
of colors range from violet to blue, blue-green, green, yellow, orange, red
and deep red. Each color represents a different wavelength of light. These
wavelengths increase in the direction from blue to red along the length of
the spectrum. The visible region of the light spectrum ranges form 400 to
700 nanometers (nm) in wavelength.
The areas extending in either direction beyond the visible spectrum are the
invisible regions of light. Below violet from 200 to 400 nm is the ultraviolet
region. Although we cannot see this light, it is reactive with photographic
materials. Therefore, it is possible to produce images that may only be observed
using photography. Extending just beyond the visible region in the other
direction from 700 nm and higher is the infrared region of light radiation.
The range of infrared light close to the visible spectrum is also
photographically reactive.
There are basically three common types of film: black and white, color negative
and transparency. Film has varying degrees of sensitivity to the amount and
intensity of light. These degrees of sensitivity are referred to as ASA.
The higher the ASA number the "faster" the film. Faster film reacts quicker
to light, therefore it requires less light for proper exposure. The drawback
of using higher ASA film is that enlarged photos may appear grainy and less
detailed.
Although slide film has accurate color rendition, it lacks "latitude." Latitude
in photography is the ability to produce a good picture from a negative that
is slightly underexposed or slightly overexposed. These corrections can be
to print film through adjustments in the print processing. Slide film is
not designed for print processing and thus lacks latitude. This means that
the exposure must be exact for the photo to turn out correctly. In addition,
for use in trial situations, slides are more expensive to convert to enlargements
than print film.
Since print film offers considerable latitude in exposure, it provides a
definite advantage for those who are not expert photographers. Because
documentation of evidence requires the reproduction to be as accurate as
possible, color film is the best medium.
Yet in domestic violence photography, UV and IR techniques are often used
to see images that our eyes cannot see. These techniques are useful because
of the way our skin interacts differently with UV and IR light compared to
visible light. For these techniques black and white film offers the best
results.
There are two reasons for this. First, the top emulsion layer of all color
film which is blue, contains UV blockers preventing the exposure of the bottom
layers. Second, the blue layer that does react does not provide as much contrast
as black and white film. In addition, there is no "color" in the UV and IR
region so nothing is gained using color films.
It should also be noted that special IR film is needed for IR photography.
Normal black and white film is not sensitive to the near IR region. IR film
is sensitive from the IR region to the UV region and may be used for both
techniques.
Polaroid Corporation has an active market in domestic abuse photography by
utilizing their pack films and instant cameras. These systems work well when
instant results are necessary. However, the color balance is not comparable
to print film, and either duplicates or enlargements must be made by
re-photographing the Polaroid picture with print film. Despite its shortcomings,
the simplicity of the instant camera may be critical if the alternative equipment
and necessary skills are not available.
For the photographic techniques illustrated in this article a 35 mm single
lens reflex (SLR) camera is needed. SLR cameras are versatile because of
interchangeable lens and filter adapters which are necessary for abuse
photography.
To obtain adequate detail, close-up photography is essential for the techniques
that will be outlined. The SLR camera incorporates a mirror and a prism that
enables the subject to be viewed through the camera lens. This allows the
photographer to document exactly what is framed by the viewfinder without
"chopping off" the subject or getting out of focus.
35 MM point-and-shoot cameras will not work. The minimum focusing distance
(approximately 3 feet) is not adequate to fill a frame. Built-in wide angle
lens and the viewfinder optics used for framing and focusing are separate
from the lens. With a point-and-shoot camera, the photographer may be able
to focus the subject in the viewfinder, but the picture will be either out
of focus of "chopped off" because the lens is not able to focus.
For domestic violence photography a shorter focal length is better. A f1.4
to f1.8 normal or macro lens is good enough to get close to the subject for
detailed pictures. Most of the photographs taken in domestic violence photography
will be taken at the minimum focusing distance to "fill the frame."
For UV photography the lens must transmit light into the UV region. However,
most lenses have been treated with a coating that blocks UV light. If money
is not an issue then an expensive quartz lens may be purchased. On the other
hand if money is a concern the alternative is to check the ability of a lens
to transmit UV light. This is accomplished by performing an analysis to determine
the percent transmittance of light less than 400 nm with a spectrophotometer.
If the lens does not transmit light in this region of the spectrum it will
not work for UV photography.
In photography controlling light is essential to obtain the proper exposure
of film. This is achieved by manipulating the reciprocity law of photochemistry.
The law states that exposure (E) is equal to the product of intensity (I)
multiplied by the time (T). E=I x T
The shutter speed on a camera determines the amount of time the film is exposed.
The settings on a given camera may range from 1 second to 1/1000 of a second.
Proceeding from 1 second each step down reduces the time by one half. An
example of shutter-scale markings would be as follows:
1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000
Intensity is dependent on the maximum amount of light available and may be
reduced by adjusting the aperture on the camera. The aperture is a diaphragm
of metal leaves forming a nearly circular opening that the light has to pass
through in order to reach the film. The range of aperture sizes are adjusted
by turning a ring on the outside of the lens. The aperture settings (f-stops
or f/numbers) usually consist of the following sequence: 1.4, 2, 2.8, 4,
5.6, 8, 11, 16, ... The smallest f/number is the largest opening, while the
largest number is the smallest opening. For every consecutive increase in
the f/number, the amount of light is decreased by half.
Because domestic violence photography is done indoors the light sources used
have relatively low intensities compared to sunlight. Therefore the choice
of film and the settings for the aperture and shutter speed need to be adjusted
to allow enough light to reach the film while still being able to hold the
camera. It is possible to "blur" a picture when holding a camera if the film
and the shutter speed are too slow. This problem may be avoided by choosing
a fast film such as 1600 ASA, in addition to setting the aperture shutter
speed pairing based on the cameras built-in light meter. It is important
that the camera has a built in light-meter, as photographing without one
will be nearly impossible.
The light source is another variable that may need to be manipulated in order
to obtain enough light for proper exposure. Because light waves spread out
as they travel away form the source, the farther away the light source is
from the subject the less light there is being focused on the
subject.
The relationship between light intensity and distance is as follows: the
light that falls on the subject is inversely proportional to the square of
the distance. This relationship is known as the inverse square law. What
this means to the photographer is that the intensity of light falling on
the subject can be doubled by decreasing the distance from the source to
the subject by half.
Penetration and reflection of light on the skin is a function of wavelength.
Shorter wavelengths such as UV do not penetrate the skin very far before
it is reflected back to the camera. Therefore a high resolution picture of
the skin surface is possible. This works well for bite marks, cuts, scratches
and scars. This is not a good technique to apply to bruises unless the blood
accumulation is very close to the skin surface.
UV Photography can be accomplished with an ordinary 35mm SLR if the lens
is capable of transmitting light somewhere between 300 nm to 400 nm. The
easiest way to make that determination is to place the lens in a
spectrophotometer and test it. Most clinical, university or forensic laboratories
have one available. Manufacturers coat most lenses to prevent excess UV
penetration. Excess UV will unbalance a color photograph with excess blue.
There isn't a common lens manufacturer that can be recommended. Some lenses
will allow UV light transmission down to the 350 nm range and some will not.
A simple test in the absence of a spectrophotometer is to photograph someone
with freckles. The appearance of freckles in UV light is considerably enhanced
compared to standard visible range light photography. No focus correction
is necessary. Success in UV photography is also a function of light intensity
(I) in the absence of the other wavelengths. To handhold photograph a living
object requires a high intensity source such as an Omnichrome 1000 or Omnichrome
FLS 5000 and a dark room. Photography with small handheld UV sources is possible,
but standardization of source-to-target and lens-to target distance are critical.
The following features are a good starting point for UV photography:
35mm SLR with fl.4 or 1.8 normal lens
3200 ASA Black and White film
UV source
Room without windows to turn out the room lights
Measuring scale-to-place near injuries
If there is a need for macro photography, avoid complex lenses and use extension
tubes. Proper light metering with a through-the-lens light meter is close
enough that bracketing your shots will lead to a quality photograph.
After an assault the victims' injuries may be photographed any time within
the next two to five days. Visible light penetrates deeper into the skin
than UV light and is sufficient to document most bruises. The addition of
special wavelength sources and special filters can improve the visualization
of the injuries by enhancing the blue color and improving the contrast against
the normal skin tones.
The equipment of choice again is a 35mm SLR with a fast lens. No special
wavelength considerations are necessary. Most of the shots are at the minimum
focusing position on the lens and available light as opposed to flash. If
the room has florescent lights be sure to use a correction filter such as
the Cokin A.036. Standard documentation with available light is usually followed
with special wavelength photography that is sometimes called "Alternate light
photography" (ALP). The Omnichrome 1000 or the Omnichrome FLS 5000 have positions
for 450 and 485 nm that emit a blue light that improves the visibility of
bruises. High ASA films such as Kodak Gold 1600, Ektapress 1600 or Fujicolor
Super HG 1600 are the films of choice. ALP in combination with an orange
filter (Cokin A.002) requires a fast film for handheld photography.
Through-the-lens light metering is accurate with visible and ALP photography.
Beware of using a white ruler or measuring tape in close-up pictures. The
meter may take the light reading of the scale and the skin tones and injury
will be too dark. This can be avoided by keeping the scales at the edge of
the photo since most light meters are center weighted.
The crime victim should be accompanied by a Victim's Assistant from the District
Attorney's office when being transported to the laboratory. A short interview
is conducted to determine the location of the injuries and how the injuries
occurred. Bruises are transfer patterns. The victim's statements may be supported
by placing fingers on the finger marks or blunt instruments over blunt injury
bruises. If a weapon was used, be sure to bring it to the photos session
whenever possible. Rough anatomical drawings and a standardized form are
used to determine the time interval for each injury. Any scars or birthmarks
are also noted.
After the interview the photographic procedure is as follows;
Place an 18% gray scale against the arm of the victim to aid the developer
in assigning the proper skin tones. Also identify the victim and include
a case number for reference.
Starting with visible light photo techniques, photograph the upper half of
the victim for identification purposes.
Photograph the general area or appendage where the injury occurs.
Adjust the lens to the minimum focusing distance and photograph the injury.
(Small injuries may require the use of extension tubes). Place a scale in
the photos.
Look for patterns in the bruising. Re-photograph with suspect's weapon adjacent
to the bruise, then directly over the bruise. If the finger marks are on
one side, look for the thumb mark on the other side.
Repeat the sequence with the ALP source and appropriate filters with the
room lights out.
If UV photography is a consideration, change to 3200 ASA black and white film and repeat the sequence with a UV source. Bracket these shots extensively.
The methods discussed above have been employed for the last year in casework
and are the result of extensive literature review and research on how to
best represent the victims of domestic violence. All cases are by appointment
to contain the labor costs. The methods have found application not only to
spousal abuse or child abuse, but also to rape victims and homicide victims
prior to autopsy and homicide suspects to document their injuries or lack
of injuries. These techniques could be applied to elder abuse and fatal traffic
accidents to identify the driver.
Most of the domestic abuse cases that have been photographed in the laboratory
have been prosecuted or resolved in a positive manner. This is a direct reversal
to the national statistics associated with domestic violence. One surprise
that has occurred is the upgrade of charges when ligature marks can be
documented. In one recent case the photography resulted in the grand jury
upgrading the charges from Assault IV to Attempted Murder. The case went
to trial and the suspect was found guilty of Attempted Murder. Of course
this is the exception as most cases end with the abuser pleading guilty and
getting a diversion to counseling. If the photography is done properly the
abuser has lost his leverage over the victim and the case may proceed without
the victim's testimony. After all, let's look at the reality of the circumstance,
"Mrs. Smith, is this you in the photograph?" or, "Mr. Smith, is this your
wife?"
The Practical Methodology of Forensic Photography David R Redsicker, Elsevier,
New York, New York 1991
Hyzer, W. G., Krauss, T.C. "The Bite Mark Standard Reference Scale - ABFO
No. 2." Journal of Forensic Sciences, JFSCA, Vol. 33, No. 2 March 1988 pp
498 - 506
West, M. H., Barsley, R E., Hall, J. E. Hayne, S. and Cimrmancic M. "The
Detection and Documentation of Trace Wound Patterns by the Use of Alternative
Light Source," Journal of Forensic Sciences, JFSCA, Vol. 37, No. 6, November
1992 pp 1480- 1488
Krauss, T. C. "Forensic Evidence Documentation Using Reflective Ultraviolet
Photography," Photo Electronic Imaging, February 1993 pp 18 - 23
Krauss, T. C., Warlen, S. C. "The Forensic Science Use of Reflective Ultra
Violet Photography," Journal of Forensic Sciences, JFSCA, Vol 30, No. 1,
January 1985 pp 262 - 268
Ultra Violet and Fluorescence Photography, Eastman Kodak Publication M -
27
McEvoy, R T. Reflective UV Photography, IX Log 911, Eastman Kodak Rochester, New York (1987)