Dynamic bare footprints differ from static bare footprints through the presence of additional, lighter markings around the rear of the heel print and apices of the toe print areas. These images can appropriately be described as inner dark and outer ghosting features. To date, the functional cause of both features has not been understood. To gain such an understanding could potentially allow the further development and use of these features in forensic identification. The aim of this project was to investigate the causes of the inner dark and outer ghosting features seen in dynamic bare footprints through an observational, practice-based action research approach within a gait laboratory. Volunteer male participants provided bare footprints on inkless paper taped to a Kistler force plate with video cameras situated either side. Ground reaction force data were collected as the footprints were formed and the event recorded using video cameras to allow these data to be correlated later. The findings suggest that the ghosting at the heel is the result of splaying of the fibro fatty pad, while that at the toes is the result of the distal ends of the toes coming into contact with the ground as the heel is lifted. Footprint, ground reaction force and video data comparisons showed that the inner dark area of the heel print corresponded with the main body of the heel contacting the ground. Outer ghosting corresponded with a backward splaying of the fat pad and the heel strike transient spike in vertical ground reaction force during increased loading. The inner dark area of the toes corresponded with a longer period of toe contact with the ground. Outer ghosting corresponded with the decreasing vertical ground reaction force and shorter contact time as the toes were leaving the ground towards the end of the contact phase of gait. Although the sample size was limited, these are new appreciations which could facilitate the use of the inner dark features in identification to provide additional points for comparison in cases involving dynamic bare footprints. Further work is now indicated to study these features in different populations and under varying conditions.

Footprints are left, or obtained, in a variety of scenarios from crime scenes to anthropological investigations. Determining the sex of a footprint can be useful in screening such impressions and attempts have been made to do so using single or multi landmark distances, shape analyses and via the density of friction ridges. Here we explore the relative importance of different components in sexing two-dimensional foot impressions namely, size, shape and texture. We use a machine learning approach and compare this to more traditional methods of discrimination. Two datasets are used, a pilot data set collected from students at Bournemouth University (N = 196) and a larger data set collected by podiatrists at Sheffield NHS Teaching Hospital (N = 2677). Our convolutional neural network can sex a footprint with accuracy of around 90% on a test set of N = 267 footprint images using all image components, which is better than an expert can achieve. However, the quality of the impressions impacts on this success rate, but the results are promising and in time it may be possible to create an automated screening algorithm in which practitioners of whatever sort (medical or forensic) can obtain a first order sexing of a two-dimensional footprint.

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Forensic gait analysis is the analysis, comparison and evaluation of features of gait to assist in the investigation of crime. Analysis refers to the process of observing features of gait and assessing their reliability for use in comparison, within the limitations of the quality of the footage. Forensic gait analysis often uses closed circuit television (CCTV) cameras to view the figure of interest. A limitation associated with using CCTV cameras is the viewing angle provided of the figure of interest. The aim of this study was to test the effect of viewing angle on observations made about the orientation of a figure's feet whilst the figure was walking. The results will supplement the forensic gait analyst's understanding of uncertainty measures. An opportunistic sample of 31 participants, with some knowledge of observational gait analysis, was recruited. Each participant viewed nine clips of an Avatar walking with its feet abducted to 30 degrees. Viewing angles ranged from 0 degrees to 180 degrees in 22.5 degree increments from the Avatar's left side. Participants were asked to comment on the orientation of both the left and right feet. The most reliable viewing angle to make judgements about the orientation of the feet was in the frontal plane, from the rear of the avatar. The most unreliable viewing angle was obliquely, from the front and side of the avatar. More incorrect judgements were made about the foot situated furthest from the camera, than the foot closest to it. Viewing angle relative to the figure being observed can influence judgements about angle of gait, and practitioners should be mindful of this when analysing, comparing and evaluating this feature as part of forensic gait analysis. The effect of viewing angle on observations of foot orientation in forensic gait analysis

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