Statistical Comparison of Forensic Toolmarks

• Activity Number: 469
• Type: Contributed
• Date/Time: Wednesday, August 3, 2011 : 8:30 AM to 10:20 AM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): Amy B. Hoeksema*+
• Companies: Iowa State University
• Keywords: Forensics ; Profilometry ; Surface characterization ; Matching ; U-statistics ; Correlated data

Abstract

In forensics, fingerprints can be used to uniquely identify suspects in a crime. Similarly, a toolmark left at a crime scene can be used to identify the tool that was used. However, the current practice of identifying a match involves visual inspection of marks which can be a very subjective process. As a result of this subjectivity, declared matches are often successfully challenged in court, so law enforcement agencies are particularly interested in encouraging research in more objective approaches. We are working to develop a statistical algorithm that can be used to determine a match or non-match given a crime mark and a suspect tool. Our analysis is based on comparisons of profilometry data, essentially depth contours of a toolmark surface taken along a linear path. With sufficient development, such methods may lead to more defensible forensic analyses.