Enhancement of Footwear Impression Evidence
A high percentage of footwear impressions produced at crime scenes are either latent or scarcely visible because of their poor contrast with the substrate. They often go undetected if various methods are not used to search for and increase their visualization. Enhancement methods increase the number of impressions detected at a crime scene as well as increase their detail available for examination. The chapter focuses on some of the more successful methods for enhancement of bloody impressions. Enhancement of two-dimensional impressions can be divided into methods that utilize alternate light sources, specialized lighting, and forensic photography; physical methods such as powdering and lifting; chemical reagents for bloody and nonblood impressions; and digital enhancement techniques. Sequencing refers to the practice of first recording and enhancing impression evidence with the use of nondestructive methods followed by those least likely to degrade the impression, and finally with those that may have success but may prevent or restrict the use of subsequent techniques.