The Forensic Imaging section of the laboratory supports the Forensic Science, Toxicology, and Medical Examiner's departments by documenting evidence, crime scenes, and autopsies. The imaging section is also responsible for Forensic Audio, Video, and Image analysis, as well as the design of displays for court, training, and the web.
Photography
Documentation of evidence is important in many aspects of a case and can range from simply recording the condition of evidence to enhancing details that may not be discernable to the human eye. General evidence documentation is performed to save a visual record of the evidence. The evidence is placed on a seamless background, evenly lit, and then photographed both front and back. Some items also require close-up photographs to show aspects of the evidence that may be important to a case.
Various methods are often used to aid in the search for evidence. To photograph these types of evidence special techniques must be employed. When documenting alternate light source fluorescence the room is darkened and a filter is placed over the lens to block the excitation energy or color of the light source. This ensures that only the fluorescent reaction is recorded.
Bluestar, a reagent used to search for blood, produces a chemiluminescent or glowing reaction that must be recorded in total darkness. This type of documentation typically requires long exposure times and high-sensitivity camera systems.
Since Gunshot Residue, or GSR, is often difficult to see, especially on dark clothing, it is documented using Infrared radiation. The reason for this is that GSR absorbs infrared radiation, while fibers, mainly those from natural materials, will reflect infrared radiation. In the resulting photographs, the GSR will look dark while the clothing will appear light, making it easier to visualize gunshot residue patterns.
Documentation of impression evidence requires that photographs be taken in several stages of the analysis. First, the impression is photographed using lighting techniques that bring out the appropriate details. Then the item suspected of making the impression, often a shoe or tire, is photographed. These photographs will be printed 1:1, or actual size, and can be used by an analyst to make comparisons. Overlays can also be made of these items by printing the images on clear transparent material. The overlay allows viewers to compare impressions by placing one on top of the other.
Audio, Video, and Image Analysis
Closed circuit television or surveillance cameras are everywhere, so there is a good chance that a crime or the events surrounding a crime were captured on video.
The lab's capabilities allow us to process video from several types of camera systems and provide investigators with a visual record of events before, during, and after a crime has taken place.
It is also possible to enhance video footage to clarify details; enhancement techniques include demultiplexing, frame averaging, perspective correction, image deblurring, magnification, and exporting still images from video. Audio enhancements include amplification, speed changes, hum, buzz, and noise removal. Image Analysis includes height examinations from video comparison analysis and video and image authentication.