Impression evidence can be generally defined as objects or materials that have retained the characteristics of other objects or materials through direct contact. Footwear and tire tread impressions are the most common types of impression evidence.
Footwear examinations are less common than fingerprint examinations. There are several reasons for this. First, such marks are not as commonly sought or recovered by crime scene investigators. Second, the clarity of reproduction required for conclusive individualization is not as often present. Third, individualization is only possible when random, individual characteristics have been imparted to the sole of the shoe that are reproduced in the impression. When this individual detail is present in sufficient quantity and quality, it is possible to individualize an impression to a specific shoe.
Tire Tread Impressions
Vehicles also leave impressions at or near the crime scene. Tire tread impressions are even less common than footwear impressions.The Forensic Examiner attains the skill to visualize and enhance these types of impressions through a set of procedures. As a form of physical evidence, footwear and tire tread impressions provide an important link between the suspect and the scene of the crime.