There are many different kinds of evidence that can be gathered from a crime scene. Footprints from footwear, feet and tires can be be left in blood or dust on a firm base. Footwear impressions occur when the footwear treads in some moldable material like the earth, clay or snow. To preserve the print a colored and sized rubber-gelatin lifter can be used to take the footprint in as evidence. Footwear evidence like a footprint in the snow should be photographed. Paint is another form of evidence that can be used in a crime scene. Sometimes the paint is transferred as fresh smears, dried chips or chalking from old, dry paint. Transfers can occur in hit and run accidents between vehicles. In those instances a photograph would be taken, however in other instances paint chips can be collected with clear tape. Glass is a frequently encountered type of evidence. If the fragments are large enough, a fracture match could be conducted to see where the glass came from. There are six different types of fractures in glass; concentric, cone or crater, hackle, radial, ream and wallner lines. Glass should not be collected with tape, rather it should be placed in a canister or plastic pill bottle to be held until sent to the laboratory. Fibers, cloth fragments and impressions are another popular form of evidence. Cloth fragments and fibers should be packaged in a pillbox or in a folded paper that is taped shut. String, cord and rope are often found in robbery, criminal homicide, rape and abduction cases. When this sort of evidence is collected, knots should not be severed and a tag should be placed on it to identify who cut the rope. Fingerprints are another common form of evidence that can be taken from the palm, fingers, toes and the soles of the feet. Powders and chemicals can be used to collect the fingerprint from the crime scene. Dental evidence can be used to identify bite-marks, and to identify subjects that are a part of the crime. Hair, when found on scene can be used as a way to identify the DNA that it originates from. Blood can be used and examined, especially when there is a blood splatter, to see exactly what happened. Photographs are used to document the evidence as well as collecting a sample from the highest concentrated area. If the blood happens to be on a material, allow for it to dry before collecting it. Firearms are often found in murder, aggravated-assault, robbery, rape, drug, kidnapping and suicide cases. The gun should be ensured to be in safety mode or handled appropriately if it is fully loaded. Never pick up the firearm until its location has been documented and photographed. Once that has been done, fingerprints should be obtained and the gun should be placed in a box with any bullets or cartridge cases.
The location of physical evidence in a crime is important but how you preserve it is also important. In order to legally use evidence an investigator must, identify every item of evidence collected or handled, describe the location and condition of the evidence at time it was collected, be able to state who had contact with or handled it and time periods, state why evidence was handled, state if changes were made and why. Methods used in documenting crime scenes: Digital Video Recording can use immediate play back and audio which gives more accuracy and quick learning and viewing. Second is Digital Still Photography which is the primary focus (pun intended) for major crime scenes as they give better angles, such as close ups, identification, relationship, and orientation. Last Is the Sketching method which gives important views such as where pieces of evidence were located or sketching views which gives overhead, elevation, or cross-projection view so objects of interest can be mapped out in the room.