Crime Scene Photography
This forensic photography discipline supports all the other disciplines by recording and documenting evidence found, gathered and analyzed in the form of photographs. For instance, in the case of the toxicology department, crime scene photos are used to document autopsies and established medical findings that were the cause of death.
Documenting evidence is a very significant aspect of any case; not only does it capture the condition of the evidence in a crime scene but it also enhances certain details that are not easily discernible to the human eye. Crime scene photography works by saving a record of a crime scene and all the evidence gathered, for investigation and future reference. To do this, items collected as evidence are photographed on a seamless background that is evenly lit. Some items such as blood stains, cuts and tears on clothing may require special close-ups to document certain details. Evidence that will undergo biological changes during analysis is also documented for comparison to trace how the changes will occur.
Several tools are used to aid in the capturing of evidence in a crime scene. For instance, semen is documented by use of special ultraviolet rays, infrared film is used to capture gun shot residue on clothing and certain fibers can only be documented under different wavelengths of light.
There are also items of evidence that require special techniques to document due to their small size. The use of a bellow or an extension tube between a lens and a camera helps by increasing the magnification of tiny objects such as head lamp filaments and hair fragments. This is referred to as photomicrography.
To capture impression evidence, different crime scene photos are required for the different stages of analysis. To begin with, contrast enhancing film and lighting is used to capture the “impression”. Next, the item suspected of forming the impression, usually a tire or a shoe is captured. Once this is finalized, the crime scene photos are printed in their actual size for comparison. Usually the photographs are printed on transparent material to make an overlay which is then used to compare the test impressions to the impressions that are still unknown.
With the recent advancement in digital technology, many aspects of forensic photography have greatly improved. With digital imaging, it is now faster to capture, edit and even transfer crime scene photos than with the processing film. Importing individual frames of video has also been made possible. One technique that has arisen with this new technology is the ability to alter the perspective of an image provided it contains a scale of reference. What this means is that you can take an image that was shot at an incorrect angle and amend it so that the scale of view is the same across the plane. This has proven to be very beneficial in cases where measurements of evidence in an image are required.
Like all disciplines of forensics, the end point is usually the courtroom. With this in mind, presentation is very important especially when one has to appear before a jury. Use of displays and visual aids such as crime scene photos, has been known to simplify a case and explain to the jury all the findings. For better visual clarity, displays can be produced by using special imaging and layout software. The final crime scene photos are printed on an inkjet printer and mounted on poster boards where they can be seen easily. This is how a quality and professional display is created.
It is evident that crime scene photos play a major role in the fight against crime; without crime scene photos a lot more criminals would be walking the streets today.