Quantitative Evaluation of Footwear Evidence: Initial Workflow for an End-to-End System
Gautham Venkatasubramanian, Vighnesh Hegde, Steven Lund, Hariharan K. Iyer, Martin Herman
In the U.S., footwear examiners make decisions about the sources of crime scene shoe impressions using subjective criteria. This has raised questions about the accuracy, repeatability, reproducibility, and scientific validity of footwear examinations. Currently most footwear examiners follow a workflow that compares a questioned and test impression with regard to outsole design, size, wear and randomly acquired characteristics (RACs). We augment this workflow with computer algorithms and statistical analysis so as to improve in the following areas: (1) Quantifying the degree of correspondence between the questioned and test impressions with respect to design, size, wear, and RACs, (2) Reducing the potential for cognitive bias, and (3) Providing an empirical basis for examiner conclusions by developing a reference database of case-relevant pairs of impressions containing known mated and known non-mated impressions. Our end-to-end workflow facilitates all three of these points and is directly relatable to current practice. We demonstrate the workflow, which includes obtaining and interpreting outsole pattern scores, RAC comparison scores and final scores, on two scenarios - a pristine example (involving very high quality Everspry EverOS scanner impressions) and a mock crime scene example that more closely resembles real casework. These examples not only demonstrate the workflow but also help identify the algorithmic, computational and statistical challenges involved in improving the system for eventual deployment in casework.
, Hegde, V.
, Lund, S.
, Iyer, H.
and Herman, M.
Quantitative Evaluation of Footwear Evidence: Initial Workflow for an End-to-End System, Journal of Forensic Sciences, [online], https://doi.org/10.1111/1556-4029.14802, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931283
(Accessed October 3, 2022)