Forensic footwear examination: A systematic review of the existing literature

Systematic reviews have been shown to be useful tools mainly in terms of identifying research areas, but the approach is less common in forensic science. Systematic reviews in forensic science have generally focused on topics closely linked to medicine or to the general practice of forensic science, such as cognitive bias or misleading evidence. The value of a systematic review is dependent on its transparency and reproducibility and, it is therefore of benefit to follow established guidelines, such as those published by the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). This paper applies these guidelines to conduct an effective systematic review of the types of research that have addressed forensic footwear examination. Using this approach, it was found that overall, there is a significant body of research that has been undertaken addressing forensic footwear examination, with 427 papers in the scope of the systematic review. The results showed that the largest proportion of papers published reported the use of an algorithm to produce an automated system to code footwear marks (25.1 %). However, only a small number of papers (1.2 %) related to the actual coding process with limited research into the use of footwear intelligence (2.1 %) and linking of scenes (0.7 %) which would follow on from pattern coding. Papers relating to the recovery and enhancement of footwear marks most frequently reported in the areas of casting (7.3 %), photography (6.3 %), chemical enhancement of marks in blood (5.9 %) and other chemical enhancement (5.6 %). A relatively small proportion of papers identified considered interpretation (15.5 %) and the characteristics of a footwear mark (12.2 %), with the former predominantly focused on general interpretation (5.9 %) and the latter on damage or randomly acquired features (6.1 %). Overall, the review suggested that more research is needed to address the use of footwear intelligence; to understand the properties of footwear prints used to compare and evaluate footwear marks; and to develop a robust, transparent and consistent method to interpret and express the significance of a footwear comparison. The latter would facilitate the clear and unambiguous communication of findings to the Criminal Justice System as a whole, including the expression of the uncertainty of the evidence.