Predicting Improved Near-Surface Detection Methods for Forensic Investigations

The detection of clandestine burials using near surface geophysical methods is a critical challenge in forensic investigations due to the variability of environmental conditions and the complexity of subsurface targets. This thesis seeks to address the challenge by enhancing the understanding and application of these methods, specifically examining the effects of long-term environmental variations on the effectiveness of burial identification. The central research question investigates whether geophysical techniques can consistently and reliably locate buried targets under varying site conditions over extended periods. It further explores the potential for developing criteria for algorithms that rank the suitability of various near surface geophysical methods, raising the question of whether method selection could be delegated to a computer tool or system. To address the problem, expert opinions were gathered through interviews and scenario-based questionnaires aimed at capturing the implicit knowledge and intuitive practices of experienced practitioners. The insights from these practitioners provided a detailed understanding of the decision-making process currently used in the field. This information was systematically analysed to inform the development of algorithm criteria. The feedback also highlighted common challenges and areas for improvement in applying geophysical methods, ensuring the proposed algorithms are both practical and grounded in real-world experience. To further understand the problem, a series of surveys were conducted at four variable test sites. One of these sites was revisited repeatedly over a twelve-month period, where different geophysical methods, such as Electrical Resistivity Imaging (ERI) and Ground Penetrating Radar (GPR), were deployed to monitor detectability of simulated clandestine pig burials. Additionally, magnetometry, along with ERI and GPR, was used at all four sites to detect a forensic metal target burial and at one site where simulated clandestine pig burials which had been interred for 28 months. These methods were employed to capture changes in subsurface profiles pre- and post-burial of forensic targets, focusing on how soil moisture and seasonal fluctuations influence detection success. The results reveal that environmental conditions significantly impact the efficacy of detection methods. ERI consistently detected burials in wetter environments, while GPR and magnetometry showed variable success depending on soil composition and moisture levels. The detectability of burials varied across sites and seasons, emphasising the importance of context-specific approaches. These findings suggest that optimal detection strategies must account for environmental and temporal factors, as detection is highly dependent on the environmental conditions surrounding the burial site. Based on these observations, this study proposes an approach go develop a tool that could provide tailored recommendations for forensic practitioners, thereby enhancing the accuracy and reliability of locating clandestine burials. The development of algorithm descriptions focused on several critical factors: the nature of the target, burial depth, parent material and soil characteristics, properties being detected, instrument sensitivity, field conditions, and spatial density of measurements. These algorithms described are designed to provide a systematic framework for method selection, ensuring robustness and applicability in diverse field conditions. This study’s scope was limited to specific environmental conditions and target types, and further research is needed to generalise the findings across broader contexts. Even so, the implications of this study are significant, providing a foundation for more effective forensic investigations and the future development of an adaptive and context-aware detectability prediction tool, as proposed in this thesis. Future work may explore integrating emerging technologies and refining algorithm descriptions for improved accuracy. In conclusion, this research aims to advance the field of forensic geophysics by demonstrating the critical influence of environmental dynamics on detection methods. It highlights the need for a mechanism that allows surveyors to observe findings directly and take site-specific measurements, thereby enhancing survey practice. Such practices should be universally adopted, and the results and observations of these studies or investigations should be made widely available to the profession, ultimately improving forensic investigation outcomes and influencing policy and practical applications in forensic geophysics.