SPECIAL CONSIDERATIONS

Photographs that may aid the investigation of burglary, housebreaking, or larceny offenses are essentially the same. The exterior and interior of the building or room should be photographed, with particular emphasis on suspected or actual points of entry. Any broken or damaged objects should be photographed, especial] y tool marks. Photographs should depict the point or means of entry and any evidence concerning the target of the offender (such as safe, jewelry box, wall locks, and soon) Trace evidence and fingerprints should also be photographed. When determined, the exit route of the offender should be photographed

It maybe helpful to photograph a person who is the victim of a crime such as assault, aggravated assault, or

Figure 16-19.-Construction of evidence flags.

a sex offense. Photographs should be made of any wound, injuries, stains, or other trace evidence that may be on the person or the clothing. The area in which the offense occurred should also be photographed. Written permission should be obtained before photographs are taken. If photographs of a body area normally clothed are required, a witness should be present. If the photographs are to illustrate a medical examination, the doctor should be present for verification.

Various other items of evidence should be specifically photographed. This evidence should normally be located in an overall view of the crime scene. Next, a medium-range shot should be taken of the object to show its surrounding area. A third closeup shot of the object should be made to show any peculiarities, followed by the same shot with a ruler in the picture area.

The photographer must photograph all evidence at the scene, since fragile materials could be damaged or destroyed enroute to the laboratory.

BASIC PHOTOGRAPHY INFORMATION

As mentioned earlier, photography can be a great investigative aid. There are several basic photographic terms and equipment with which you should be familiar to take usable photographs.

Lens speed. Lens speed is expressed as the largest f opening a lens has and denotes the amount of light the lens is capable of transmitting to the film. The largest f opening is the smallest f/stop number on the lens (f16 is a smaller opening than f4.5).

Shutter speed. The shutter's purpose is to vary the amount of time during which light is allowed to reach the film. The time that the shutter is open is called shutter speed This time or shutter speed maybe varied, depending on the lighting conditions and the amount of movement to be stopped. For example, the shutter speed must be fast to photograph a moving object without blur. In crime scene photography, objects will probably be still, so the shutter speed maybe slower.

Film speed. Film speed identifies the sensitivity of the film to light. Film is given a rating known as ASA Exposure Index, which will be seen as ASA 100 or ASA

800 for example. Film is classified as slow, medium, or fast. A rating up to ASA 100 is slow, ASA 100 to ASA 200 is medium, and ASA 200 to ASA 1200 is fast. The faster the ASA, the less light is required to make an acceptable photograph. Also, the faster the film speed the more grain it will produce in the photograph. Too much grain can confuse or hide small details.

Exposure meter. Also known as light meters, exposure meters accurately measure the light value of a scene or object at which it is pointed The reading this meter gives is converted into usable shutter speed and lens speed (f/stop). It is advisable to obtain an average between the lightest and darkest part of a scene.

Filters. Filters control the amount of light entering the lens of a camera. This is varied by the color and density of the filter.

Filter Uses

In black-and-white photography, you select a filter of the same color to eliminate the color and a falter opposite it on the color wheel to darken it dramatically. For example, if the subject were blue, a blue falter would lighten it and a yellow falter would darken the same subject. The investigator/photographer should read the film information sheet packaged with each roll or box of film. These sheets recommend filters for use in different situations.

Color Photography

Color film comes in two general categories- positive and negative.

Positive color film produces a positive image known as a transparency (slide). Positive color films are distinctive in that regardless of manufacturer, the brand name ending is always "chrome" (such as Ektachrome, Anscochrome).

Negative color films produce a negative image that can be used to make a positive print, positive transparency, or black and white print. Negative color films are distinctive in that regardless of manufacturer, the brand name ending is always "color" (such as Ektacolor, Anscocolor).

Negative color film is best for use in police work because it has a much greater latitude than positive material, which has a greater error factor. Color prints produced for court use must be accurate color reproductions of the subject or crime scene. Color shifts or impurities can occur when a laboratory is producing color prints, but the technician printing the color can accurately reproduce the colors of the crime scene with a color guide in one of the pictures.

You can aid the color printing technician by photographing an extra shot of the crime scene/subject, and adding a neutral density card (commonly known as a gray card) to the picture. Neutral density cards can be obtained through supply charnels. This gray card is important because the color printing technician knows how to reproduce this color, giving him or her an accurate basis for printing all other colors in that picture and all other pictures from that roll or box of film.

When attempting to present color photographs in court, always have black-and-white prints available in case the court does not accept the color prints.

Infrared and Ultraviolet Photography

All evidence requiring the use of ultraviolet or infrared photography should be sent to criminal investigation laboratory for this specialized treatment.

Some of the ways infrared photography may be used in handling evidence include examination of dirty, burned, or charred documents; writing on documents which has been erased or covered with dark ink; dyed

cloth and the structure of the weave of cloth; differences in inks, dyes, and pigments; various stains; and gunpowder residues.

Ultraviolet photography may be used to examine questioned, altered or faded documents; detect invisible inks; examine fingerprints on multicolored backgrounds; and examine seminal stains on clothing.

For further information on forensics refer to OPNAVINST 5580.1 and/or contact local NCIS in your area.

SUMMARY

In this chapter, we explained the proper procedures for fingerprinting followed by an examination of how casts and molds are used in the investigative process. Then we looked at how glass may be an important factor at a crime scene. Next, trace evidence such as tool marks, serial numbers, and other materials were considered The polygraph as an investigative aid was discussed next, in terms of its uses and limitations. Finally, we covered crime scene processing and the techniques used in crime scene photography.