This episode of the Just Science podcasts consists of an interview with Chris Hamburg from the Oregon State Police Forensic Services Division and Jeff Jagmin from the Washington State Police Crime Laboratory Division in Seattle, who discuss the process a footwear examiner follows in making test impressions for comparison.
The interview first notes that crime-scene investigators in the United States do not generally give the same priority to shoe impressions as crime investigators in the United Kingdom. British crime investigators have access to a well-developed database for footwear. Hamburg and Jagmin advise that crime-scene footwear impressions can be important in placing suspects at a crime scene and in linking separate crime scenes. The focus of the interview is on the making of the test impression from a suspect's shoe in determining whether there is a match with the crime-scene shoeprint. This is complicated, since the crime-scene shoeprint is influenced by the weight and foot size of the offender, as well as the movement of the wearer when the print was made (standing, running, walking, kicking in a door, etc.). Hamburg and Jagmin discuss some of the findings from their workshop in which participants show the differing effects of a shoeprint from the person making an original shoeprint compared with a test print made by a person with a different shoe size and body weight. At issue is the factors involved when attempting to make a comparative test print that simulates the features and activity of the wearer of the shoe that made the crime-scene print. They also discuss the importance of law enforcement agencies sharing footwear print evidence across jurisdictions in determining links between crimes.