Comparative analysis of static and dynamic bare footprint dimensions in a north Indian population

A preliminary study on the stability of bare footprint linear measurements in four motion states

In some crime scenes, there may be bare footprints. Analyzing and testing the linear measurements of bare footprints in crime scenes can play an important role in personal analysis and individual identification. However, the linear measurements of bare footprints may be influenced by different motion states, leading to changes in length and width or even significant deviations. Previous studies focused on the linear differences between static and dynamic footprints, and failed to take the speed factor into consideration. This paper studied the stability and change regularities of the linear measurements of bare footprints in four different motion states: standing, normal walking, fast walking and trotting. Dust footprints of the right feet were collected from 80 healthy young adults under these four motion states. Seven linear measurements were obtained for each footprint using the Reel method, totaling 2240 data sets. One-way repeated measures ANOVA was used to assess the measurement variations across the four states. The results showed that there were statistically significant variances in the length measurements (A1-A5) between the standing state and other motion states, whereas no statistically significant variances were observed between the three dynamic states. It was found that the mean values of the five length measurements (A1-A5) increased from static to dynamic state, and then gradually decreased slightly as the walking speed increased. Additionally, no significant differences were found in the two width measurements (MPJ Width and Calc Width) between the four motion states. As a preliminary study, this study can provide a reference for the analysis of bare footprints in different motion states extracted from crime scenes.

The importance of assessing the ghosting phenomenon in dynamic footprints when estimating stature - Forensic implications

In cases where multiple footprints are found at a crime scene, it is unusual that all are static, and some are likely dynamic. Depending on how the footprint was made, we distinguish between dynamic and static footprints. A distinguishing feature that has only recently been associated with dynamic footprints is the fact that dynamic footprints differ from static footprints by the presence of additional markings around the back of the heel and the tops of the toe prints, the so-called ghosting phenomenon. The present study aims to analyse the ghosting phenomenon on dynamic footprints - its occurrence in relation to sex, laterality, and different areas of footprints as well as length features. Additionally, it aims to investigate the assessment of the ghosting phenomenon on dynamic footprints when estimating stature for biological profiling in the forensic field. The study sample comprised of 170 young adults aged 18 - 30 years of both biological sexes. Stature was measured and dynamic footprints were obtained where the ghosting phenomenon was analysed together with length measurements of the same footprint with and without ghosting. In the first and second toes of footprints, the ghosting phenomenon occurred most frequently in both sexes and in the sex-mixed group. Sex differences were not significant in ghosting occurrence on right and left footprints (p > 0.05), except for the area of the left fifth toe (p = 0.045). All the footprints' lengths with ghosting were significantly higher (p < 0.001) than those without ghosting. Statures calculated from footprint length measurements with ghosting predicted stature more accurately than statures calculated from the same footprint length measurements without ghosting. In the case of finding dynamic footprints at crime scenes, it is necessary to correctly identify and evaluate ghosting of the footprint. This comparison can be helpful in interpreting how ghosting should be taken into account when estimating a person's stature.

Ghosting phenomenon in static and dynamic footprints in India and the United States

Ghosting is the phenomenon that exists when a footprint has a lighter area around the tip of one or more toes or a shadow-like area at the back of the heel. To date, ghosting has been considered primarily a finding of dynamic (walking) footprints, rather than static (standing) footprints. The prevalence of ghosting in static footprints is unknown, and research on its presence in static and dynamic footprints from the same participant is sparse, as are studies on its occurrence in different geographic populations. This study is among the first to evaluate the occurrence of ghosting in the static and dynamic footprints from a particular individual with participants in two geographic populations. A combination of both inkless and ink footprint collection systems were used to obtain a total of 206 bare footprints from 103 adult participants from the United States and India. The data comprised 103 static and 103 dynamic footprints. Ghosting occurred significantly in static footprints, though less frequently than in dynamic footprints. Ghosting in static footprints was seen most often at the first toe, followed by the third and second respectively. This aspect appeared least at the heel. In dynamic footprints, it occurred most at the first toe, followed by the second and fourth toes, and then the third toe and the heel. The prevalence of ghosting in footprints from the United States and India differed in their locations, notably at the first and second toes in the static footprints and at the heel in the dynamic footprints.

One size fits all? Stature estimation from footprints and the effect of substrate and speed on footprint creation

Estimation of stature from footprint lengths is a common prediction in forensic cases and in paleoanthropology upon the discovery of fossil footprints. Many studies, which have estimated stature from footprints, generally use a "one-size-fits-all" approach that usually involves applying a known ratio of foot length to total stature to do so, although this method has fallen out of practice in forensic cases in recent years but is still commonly used for fossil trace evidence. Yet, we know that substrate and speed can change the dimensions of a footprint, so why are these "one-size-fits-all" approaches still used today? We tested footprint production across different substrates at a walk, a fast walk, and a jog. We calculated how accurately footprint dimensions were impressed between these different conditions and identified sources of error in footprint lengths, and the percentage changes of how significantly a footprint can change in length between different conditions. We provide a table with different ratios that we encourage practitioners/field scientists to refer to and use when estimating stature from footprints, with respect to the substrate on which the footprint was created and the speed at which it was created. We actively encourage researchers to add the ratios by testing more substrates so that in the future stature can be more accurately estimated, thus aiding the paleoanthropological community, but also forensic investigations by statistically highlighting how different conditions can affect trace dimensions.

Recovery via SfM photogrammetry of latent footprint impressions in carpet

Impression evidence retained in carpet is usually recovered, if at all, in two dimensions via a vertical photograph. Here, we show that recovery is also possible via SfM photogrammetry and this gives good quality results that allow digital measurements both in the x-y plane and by depth (z-axis). This study focuses on recovery from polypropylene carpets which are widespread due to their resistance to wear and low cost. We show how traces can be recovered using both SfM photogrammetry and conventional photography with illumination provided via a crime scene light source. Experiments show that traces are retained for considerable time periods if left undisturbed, in excess of four weeks, but are quickly lost in under 8 hours by subsequent footfall. A simple simulation shows how the movement of an individual can be determined from carpet traces and the value of 3D recovery is illustrated via a set of experiments conducted with barefoot traces. We draw attention to the fact that 3D models allow a more statistical-based approach to be taken to match bare footprints at crime scenes. SfM photogrammetry is shown to provide a useful compliment to existing techniques and therefore worthy of further experimentation and potentially operational use.

The contact area of static and dynamic footprints: Forensic implications

When found at crime scenes, footprints may be evidentially valuable and can assist with the identity of a perpetrator based on their features and/or measurements. Footprints can be either static (made while standing) or dynamic (made while walking). While extensive research has been performed on the linear measurements obtained from static and dynamic footprints, research on the comparisons between the contact area of static and dynamic footprints in the forensic context are limited. The present study compares the contact area of static and dynamic bare footprints to determine if statistically significant differences exist between the two. Static and dynamic footprints were obtained from a sample of randomly-selected 461 Jatt Sikh adults (230 males and 231 females) of Indian origin between the ages of 19 and 32 years. The footprint contact area was calculated from each footprint (excluding the toes) using a PedoGRID® sheet. No statistically significant differences were observed between the contact area of static and dynamic footprints for each foot among males and females. However, statistically significant differences between both the sexes were found in the footprint contact areas of both footprint types. The right dynamic footprint contact area was found to be the most predictive measurement for classifying and estimating sex from a footprint's contact area. The study has implications in the analysis of footprints recovered from crime scenes.

Chasing ghosts: An investigation of the ghosting phenomenon in footprints

Ghosting is a phenomenon that has been identified in dynamic (walking) footprints. There is sparse research on the occurrence of ghosting; however, due to the forensic value of footprints and their use in other scientific fields, the phenomenon of ghosting warrants further study. Ghosting can be used to determine if a footprint is static (standing) or dynamic, which can help forensic investigators create a sequence of events at a crime scene. Furthermore, this can help in footprint comparisons from this determination, as "like versus like" comparisons of dynamic or static footprints can be made. The purpose of this research was to determine the prevalence and locations of the ghosting phenomena in dynamic footprints. 136 dynamic footprints from 68 volunteers were collected using an inkless collection system. Each footprint was visually inspected for ghosting as well as examined using software. Ghosting was present on at least one location in all footprints. The highest prevalence occurred at the tip of the great toe, followed by the second digit and the heel. To a lesser extent, ghosting appeared at the tips of the other three digits. Ghosting often occurred at two or more areas in a given footprint.