Development and evaluation of a valid and reliable footprint measurement approach in forensic identification

Introduction: Bare footprints found at a crime scene can be used as forensic evidence to link a person to the incident using comparison methods.
Identification relies upon methods of evaluation including measurement; however the science underpinning measurement in this field has not been fully explored.
Method: A critical review of the literature revealed various measurement approaches and also demonstrated little or no measurement rigour in terms of reliability and validity. Therefore a novel pragmatic method for collecting and
measuring two-dimensional bare foot impressions was developed by the researcher to provide the necessary tool for use in this field. Evaluation involved three static and three dynamic footprints collected from thirty female and thirty one male volunteers using an inkless paper system. The footprints were digitised and widths, lengths and angles constructed and automatically measured using freely vailable measurement software. Measurement rigour was pursued using modern validity and intra-/inter-rater reliability approaches followed by an evaluation of the tool by experts in the field. These explorations are presented within the thesis as separate investigations.
Results: Statistically significant differences occurred between paired static and dynamic linear measurements (df 60) with t values ranging from 3.08 to 23.17, P
< 0.01. The highest correlations with stature were shown to be the linear measurement from the heel to fifth toe print in the dynamic footprints (r = 0.858, P < 0.01). The reliability analysis found high intra-rater agreement using
intraclass correlation coefficient (ICC) 0.99 with a 95% standard error of measurement 0.84 mm, 95% limits of agreement (LOA) -0.91 to 0.65.
Conclusion: The research establishes a valid and reliable two-dimensional measurement approach, useful for footprint identification purposes and also as a baseline method for further research in this field.