Browsing by Author "Giles, Stephanie"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    The CSI effect(s no one?)
    (Elsevier, 2019-06-04) Errickson, David; Giles, Stephanie; Horsman, Graeme
  • Thumbnail Image
    ItemOpen Access
    The effectiveness of forensic evidence in the investigation of volume crime scenes
    (Elsevier, 2021-06-24) Wüllenweber, Sarah; Giles, Stephanie
    This study investigates the effectiveness of forensic evidence in UK volume crime investigations. The main aim was to identify characteristics of forensic evidence that influence its effectiveness in converting detections into criminal charges, as well as to critically consider the effectiveness of a recent service level agreement (SLA) implemented by Wiltshire Police, which aimed at reducing CSI attendance. The sample consisted of 445 police recorded cases received from Wiltshire Police. Presence or absence and location-related characteristics of fingerprint, DNA, and footwear evidence were evaluated on the effectiveness of forensic evidence and examined within the contexts of different volume crimes. Results showed a high level of correlation in converting detections into criminal charges where the presence of DNA, footwear, and multiple evidence types was recorded; and a positive correlation between forensic evidence ineffectiveness and presence of fingerprints, particularly in residential burglaries. Differences between individual offence types were expressed. The most prominent feature influencing the effectiveness of forensic evidence was found to be related to the movability of the exhibit associated with the recovered evidence, with DNA recovered from non-movable items presenting the strongest effectiveness. Cases processed after the implementation of the SLA did not show significant differences in forensic evidence effectiveness as compared to cases processed prior to the SLA, however, they demonstrated a lack in effectiveness of DNA evidence. The findings of the current research provide a better understanding of the contextual influences on the potential of forensic evidence and can support improvement of crime scene screening and CSI resource deployment.
  • Thumbnail Image
    ItemOpen Access
    Evaluation of porcine decomposition and total body score (TBS) in a central European temperate forest
    (Wiley, 2024-02-26) Indra, Lara; Giles, Stephanie; Alfsdotter, Clara; Errickson, David; Lösch, Sandra
    The total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the porcine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one “substantial agreement” category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic casework in comparable contexts in Central Europe.
  • Thumbnail Image
    ItemOpen Access
    Solving the inverse problem of post-mortem interval estimation using Bayesian Belief Networks
    (Elsevier, 2022-12-09) Giles, Stephanie; Errickson, David; Harrison, Karl; Márquez-Grant, Nicholas
    Bayesian Belief Networks (BBNs) can be applied to solve inverse problems such as the post-mortem interval (PMI) by a simple and logical graphical representation of conditional dependencies between multiple taphonomic variables and the observable decomposition effect. This study is the first cross-comparison retrospective study of human decomposition across three different geographical regions. To assess the effect of the most influential taphonomic variables on the decomposition rate (as measured by the Total Decomposition Score (TDS)), decomposition data was examined from the Forensic Anthropology Research Facility at the University of Tennessee (n = 312), the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 250), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 81). Two different BBNs for PMI estimations were created from the US and the UK training data. Sensitivity analysis was performed to identify the most influential parameters of TDS variance, with weaker variables (e.g., age, sex, clothing) being excluded during model refinement. The accuracy of the BBNs was then compared by additional validation cases: US (n = 28) and UK (n = 10). Both models conferred predictive power of the PMI and accounted for the unique combination of taphonomic variables affecting decomposition. Both models had a mean posterior probability of 86% (US) and 81% (UK) in favor of the experimental hypothesis (that the PMI was on, or less than, the prior last known alive date). Neither the US nor the UK datasets represented any cases below 'moderate' support for the value of PMI evidence. By applying coherent probabilistic reasoning to PMI estimations, one logical solution is provided to model the complexities of human decomposition that can quantify the combined effect of several uncertainties surrounding the PMI estimation. This approach communicates the PMI with an associated degree of confidence and provides predictive power on unknown PMI cases.
  • Thumbnail Image
    ItemOpen Access
    A study to assess the variables that influence the degree of mummification and skeletonization in a modern USA population
    (Equinox, 2021-05-23) Jackson-Mitchell, C.; Giles, Stephanie
    Taphonomic studies through experimental research at Forensic Anthropological Research Facilities are continuously developing our understanding of soft tissue decomposition in controlled environments. Photographic archives provide an alternative means to study decomposition using associated detailed case notes, environmental variables surrounding the death and (if known) post-mortem interval (PMI). Leccia, Alunni and Quatrehomme (2018) utilized this resource to calculate the total body surface area (TBSA) in bodies with extensive and complete mummification using “the rule of nines,” a method where the body is sectioned into nine anatomical sections to assess TBSA burnt however they did not test this statistically. This article aims to revise their study by implementing the more representative Lund and Browder chart (Yast? et al. 2015) to visually assess all degree of mummification and skeletonization, through a secondary data analysis study using autopsy photographs of 17 cases from Allegheny County Medical Examiner’s Office, Pittsburgh, between 2007–2016. Principal component analysis (PCA) was conducted on the body section scores to reveal high correlation co-efficients (>0.95) between anatomical sections indicating a high confidence, mummification and/or skeletonization on multiple body parts will co-exist on a decomposed body. PCA of recorded variables revealed that after body position was removed from analysis, the majority of variables had strong values. i.e., those with a numerically large magnitude (.750 to .850, -.767 to -.840). Multiple regression analysis and ANOVA revealed age to be the significant independent variable at 10% significance level. The results of this study have forensic application for crime scene investigators, mummification and skeletonization percentages can be effectively recorded upon examination of a body, whilst also demonstrating variables that have a significant effect on presentation of these two post-mortem changes. Further examination of globally dependant variables affecting modern mummification is encouraged.