No abstract

finding hidden bodies, believed to have been murdered and buried, is problematic, expensive in terms of human resource and currently has low success rates for law enforcement agencies. Here we present, for the first time, ten years of multidisciplinary geophysical monitoring of simulated clandestine graves using animal analogues. Results will provide forensic search teams with crucial information on optimal detection techniques, equipment configuration and datasets for comparison to active and unsolved cold case searches. electrical Resistivity (eR) surveys showed a naked burial produced large, lowresistivity anomalies for up to four years, but then the body became difficult to image. A wrapped burial had consistent small, high-resistivity anomalies for four years, then large high-resistivity anomalies until the survey period end. Ground Penetrating Radar (GPR) 110-900 MHz surveys showed the wrapped burial could be detected throughout. 225 MHz GPR data was optimal, but the naked burial was poorly imaged after six years. Results suggested conducting both eR and GpR surveys if the burial style was unknown when searching for interred remains. Surveys in winter and spring produced the best datasets, and, as post-burial time increases, surveying in these seasons became increasingly important. this multidisciplinary study provides critical new insights for law enforcement and families of the disappeared worldwide. Available statistics for missing persons globally vary. For example, in the United Kingdom, ~250,000 are reported missing every year, but, of those, only ~2,500 are still missing after a year 1. In the United States, ~650,000 are reported missing every year, but only ~90,000 are still missing after a year 2. Whilst these still missing numbers are comparatively small, for the families of the missing it is obviously of crucial importance for them to be found, not only for closure if they have been the victim of a homicide, but also to know that justice for the perpetrator(s) has been served. However, current success rates to find the missing are low, with high profile examples being Madeleine McCann in Portugal and Ben Needham in Greece, sadly both presumed dead. Forensic search methods vary widely. A search strategist may be involved in a case at an early stage to decide which methods would have the highest probability of search success 3 , but this is not for every case globally, and investigations may not be standardised or indeed different techniques undertaken, depending on local experience 4. Metal detector search teams 5-7 and specially-trained victim recovery dogs 7-9 are both commonly used during initial investigations or as part of phased sequential search programmes. Forensic investigators have been increasingly using geoforensic methods in civil or criminal forensic investigations, predominantly to assist search teams as they attempt to locate missing persons or for trace evidence purposes 10-13. Locating homicide victims buried within clandestine graves is one of the most important and difficult ch...

This ongoing monitoring study provides forensic search teams with systematic geophysical data over simulated clandestine graves for comparison to active cases. Simulated “wrapped,” “naked,” and “control” burials were created. Multiple geophysical surveys were collected over 6 years, here showing data from 4 to 6 years after burial. Electrical resistivity (twin electrode and ERI), multifrequency GPR, grave and background soil water were collected. Resistivity surveys revealed that the naked burial had low‐resistivity anomalies up to year four but then difficult to image, whereas the wrapped burial had consistent large high‐resistivity anomalies. GPR 110‐ to 900‐MHz frequency surveys showed that the wrapped burial could be detected throughout, but the naked burial was either not detectable or poorly resolved. 225‐MHz frequency GPR data were optimal. Soil water analyses showed decreasing (years 4 to 5) to background (year 6) conductivity values. Results suggest both resistivity and GPR surveying if burial style unknown, with winter to spring surveys optimal and increasingly important as time increases.

19Graveyards and cemeteries around the world are being increasingly designated as full. 20There is a growing requirement to identify burial spaces or to exhume and then re-inter 21 burials if necessary. Near-surface geophysical methods offer a potentially non-invasive 22 target detection solution; however there has been lack of research to identify optimal 23 detection methods using such geophysical techniques. This study has collected multi-24 frequency (225 MHz -900 MHz) ground penetrating radar, electrical resistivity and 25 magnetic susceptibility surface data over known burial sites with different burial ages and 26 UK church graveyards. Results indicate that progressively older burials are more difficult to 27 detect but successful grave detection is complicated by soil type. Different geophysical 28 techniques were optimal in the three sites surveyed, which therefore suggests a multi-29 technique approach should be utilised by survey practitioners. Graveyard geophysical targets 30 included the grave soil present above earth-cut graves, the grave contents themselves, brick-31 lining (if present) and grave soil leachate plumes that are all geophysically detectable from 32 background levels. Grave markers were also identified as not always being located where the 33 burials were positioned. This study clearly demonstrates the value of these techniques in 34 grave detection and inform search teams detecting clandestine burials. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Globally, graveyards and cemeteries are suffering from a severe lack of burial space. 42With an estimated 55 million individuals dying globally each year (de Sousa, 2015), the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 (Reynolds, 2011; Pringle et al. 2012a Pringle et al. /2016 Gaffney et al. 2015). Electrical resistivity 77 surveys have been successfully used to locate unmarked burials in cemeteries (see, e.g. 78Matias et al. 2006; Hansen et al. 2014; Buyuksarac et al. 2015). Controlled studies on 79 modern burials evidencing that decompositional fluids may be the dominant factor in graves 80 that is detected electrically (see Jervis et al. 2009; Pringle et al. 2012b), and may be retained 81 in grave soil for considerable periods of time post-burial (see Pringle et al. 2015a). However, 82it is important to note that the style of formal burials and clandestine graves of murder 83 victims are usually quite different in terms of structure, depth and complexity of the burial 84 contents (Fig. 1). Apart from graveyards and cemeteries being reused, partially excavated, 85topsoil removed, etc. the graves present can also vary in style from earth-cut (as shown in 86 Fig. 1) to...

Colombian forensic investigators required assistance locating clandestine burials of missing persons related to human right atrocities from 14 years ago. Geoscientific search methods were trialled, including a predictive spatial statistical model, using various input and database information, to select the most likely grave locations in difficult mountainous terrain. Groundwork using forensic geomorphology, near‐surface geophysics (ERT) and subsequent probing identified suspect burial positions. One site was in mountainous terrain and the other in former school grounds, both difficult to access and in poor weather conditions. In the mountainous area, a negative resistivity anomaly area was identified and intrusively investigated, found to be a buried rock. In school grounds, after MESP and intelligence were used to identify a burial site, surface depressions were identified, and ERT datasets collected over the highest priority depression; intrusive investigations discovered a hand‐dug pit containing animal bones. This approach is suggested for Latin American searches.