During the past eight decades, several forensic science tools have been developed to aid criminal justice agencies in the performance of their duties. These tools for the careful testing and comparison of tangible evidence are used both to prosecute the guilty and to exonerate the innocent. Fingerprints can place particular persons at particular places and indicate they have handled particular items; they are valuable for both criminal and civil identifications. Footwear or tire track impressions at or near a crime scene provide important evidence that is photographed, collected, and processed for comparison and identification purposes. When palm prints and footprints can be detected at a crime scene, perpetrators can often be identified from such evidence. Handwritten, handprinted, typed, or printed documents sometimes serve to tie a suspect to a crime. Microscopic comparisons of fired bullets and shells can determine whether they were fired from a particular weapon or suggest the kind of weapon used in the crime. Other means of identification are through dental analysis, voiceprint analysis, patterns of ear design, a composite sketch, eye analysis, and DNA analysis.