When all is Tread and Done! (Police STAR Fund final report)

Information held within CCTV footage used to assist the identification process can include clothing comparison, facial comparison, height analysis and gait analysis. However, there is little literature documenting the analysis and comparison of footwear captured in CCTV, body worn video (BWV) or mobile downloads. This highlights the underuse of this form of evidence for identification purposes. The footwear unit at Yorkshire and the Humber Regional Scientific Support Services has identified footwear comparisons of uppers caught on camera as a growth industry following the observed increase in ad hoc casework, including requests from other forces and the National Crime Agency. Without promoting this area of business, the unit has seen 10% growth in evidential submissions, this excludes screening requests and intelligence reports. As of 2019, there has been a steady increase in the number of enquiries and comparisons performed. However, forensic practitioners have limited resources to help identify the make and model of footwear recorded in footage. Therefore, the project aimed to develop a searchable database of 360-degree footwear images (uppers and treads) under visible and near infrared light. It was anticipated that the images would be interactive, pivoting on an axis to enable the user to move the footwear to the required viewing angle. It was necessary for the selected image capture method to be cost-effective, efficient and capable of producing 3D models in white and near infrared light that can be uploaded to a database.
The project's structure consisted of four work packages: project management, principles and practices exploration, method development and database design/ data collection. A literature search highlighted there is a lack of published knowledge surrounding the absorption and reflection of near infrared (at 850nm) on natural and synthetic materials and dyes/pigments. The 850nm wavelength was of most interest, due to CCTV research demonstrating that semi-covert security cameras use 850nm to view in night vision. The quality and repeatability between a sample of cameras was tested to contribute towards the image capture method. A converted infrared DSLR camera along with multiple home and business security cameras were used. The footwear sample imaged as part of this test included 49 pairs of shoes from a range of brands such as Adidas, Nike and Puma. The tests showed there were differences between resultant images when reflective material was present on the shoe upper. Therefore, the converted DSLR camera was excluded from the image capture method, as it did not produce a ‘like with like’ product. After trialing different backgrounds, lighting conditions, angle of camera/shoe and multiple shoes, only one e-commerce out of the three initially selected for testing was reliable. The results were used to produce two separate standard operating procedures to create 360-degree images and 2D still images. The footwear sample was used to begin the initial design stages of a footwear upper database. Database v.1 showed proof of concept, and now the National Footwear Operations Group are working on a version to simplify the search criteria based on the exisitng decision tree approach used in the National Footwear System.
From the literature search and observations made during phase 1, questions have arisen regarding the commonality and frequency of certain manufactured and acquired characteristics on the footwear. Therefore, the next stages of this research will investigate factors that influence the interpretation of class and individual characteristics (e.g. brand and damage, respectively) that could influence the evidential outcome of a comparison.