Optimizing search strategies in mass grave location through the combination of digital technologies

Discrimination of human and animal bloodstains using hyperspectral imaging

Blood is the most encountered type of biological evidence in violent crimes and contains pertinent information to a forensic investigation. The false presumption that blood encountered at a crime scene is human may not be realised until after costly and sample-consuming tests are performed. To address the question of blood origin, the novel application of visible-near infrared hyperspectral imaging (HSI) is used for the detection and discrimination of human and animal bloodstains. The HSI system used is a portable, non-contact, non-destructive method for the determination of blood origin. A support vector machine (SVM) binary classifier was trained for the discrimination of bloodstains of human (n = 20) and five animal species: pig (n = 20), mouse (n = 16), rat (n = 5), rabbit (n = 5), and cow (n = 20). On an independent test set, the SVM model achieved accuracy, precision, sensitivity, and specificity values of 96, 97, 95, and 96%, respectively. Segmented images of bloodstains aged over a period of two months were produced, allowing for the clear visualisation of the discrimination of human and animal bloodstains. The inclusion of such a system in a forensic investigation workflow not only removes ambiguity surrounding blood origin, but can potentially be used in tandem with HSI bloodstain age determination methods for rapid on-scene forensic analysis.

Optimizing coastal exhumation strategies: the casework of the Committee on Missing Persons in Cyprus (2006-2022)

This paper reports on coastal exhumations performed during 2006-2022, under the framework of the Committee on Missing Persons in Cyprus (CMP) humanitarian identification programme. CMP archaeologists investigated 217 coastal locations and recovered skeletal remains on 44 occasions. Challenging environmental conditions required a customized exhumation plan, which could be executed swiftly without compromising operational integrity or standards. The author performed a retrospective analysis to propose an optimized strategy, which includes a survey, exhumation, digital documentation, and post-processing components, with the aim of minimizing the effects of adverse environmental conditions. The proposed strategy is based on scientific standards and observations in the field; it can satisfy the needs of a humanitarian or criminal investigation if appropriate measures are taken to uphold legislative and forensic standards. The author also discussed the taphonomic effects of coastal erosion and wave activity in tandem with exhumation recommendations to assist forensic practitioners involved in similar investigations.

Improving witness interviewing for the investigation of disappeared persons due to armed conflict

Investigating missing persons who are presumed dead in conflict contexts almost always involves witness interviews. Interviews can be critical both to locating burial sites and to positively identifying bodies that are located. Despite the importance of interviews, the authors have found that investigators in these contexts seldom have formal training on interviewing. This article highlights three principal problems that the authors have experienced relative to interviewing as part of missing persons investigations in armed conflict contexts: that interviewing is not treated as a professional activity; the tendency to overvalue technical tools in the search for burial sites; and a lack of awareness about cultural and contextual factors that impact interviews. The article concludes with five recommendations on how to improve witness interviewing.

Systematic Approach for Remote Sensing of Historical Conflict Landscapes with UAV-Based Laserscanning

In order to locate historical traces, drone-based Laserscanning has become increasingly popular in archaeological prospection and historical conflict landscapes research. The low resolution of aircraft-based Laserscanning is not suitable for small-scale detailed analysis so that high-resolution UAV-based LiDAR data are required. However, many of the existing studies lack a systematic approach to UAV-LiDAR data acquisition and point cloud filtering. We use this methodology to detect anthropogenic terrain anomalies. In this study, we systematically investigated different influencing factors on UAV-LiDAR data acquisition. The flight parameters speed and altitude above ground were systematically varied. In addition, different vegetation cover and seasonal acquisition times were compared, and we evaluated three different types of filter algorithms to separate ground from non-ground. It could be seen from our experiments that for the detection of subsurface anomalies in treeless open terrain, higher flight speeds like 6 m/s were feasible. Regarding the flight altitude, we recommend an altitude of 50-75 m above ground. At higher flight altitudes of 100-120 m above ground, there is the risk that terrain characteristics smaller than 50 cm will be missed. Areas covered with deciduous forest should only be surveyed during leaf-off season. In the presence of low-level vegetation (small bushes and shrubs with a height of up to 2 m), it turned out that the morphological filter was the most suitable. In tree-covered areas with total absence of near ground vegetation, however, the choice of filter algorithm plays only a subordinate role, especially during winter where the resulting ground point densities have a percentage deviation of less than 6% from each other.

Using Ground Penetrating Radar and Resistivity Methods to Locate Unmarked Graves: A Review

The location of unmarked graves in forensic and archaeological investigations is legally and culturally important. In a forensic context, locating covert burials of missing persons can provide closure to the family, as well as facilitating the successful prosecution of the individual(s) responsible. Archaeologically, burials provide an important source of information about health, diet, physical anthropology, and culture. Despite the importance of these features, the location of unmarked graves with conventional archaeological and forensic techniques, such as excavation, is difficult and expensive. As a result, geophysical techniques have been widely applied to the location of unmarked graves as they are non-invasive, cost and time effective, and avoid the unnecessary disturbance of human remains. This article brings together the literature on ground penetrating radar (GPR), and two resistivity methods, electrical resistivity tomography (ERT) and fixed probe resistivity (FPR), on their ability to locate burials and reviews their use in forensic and archaeological investigations. This paper aims to provide law enforcement personnel, archaeologists, geophysicists, and interested academics with an overview of how these techniques work, how they have been previously applied to grave detection, and the strengths and weakness of these methods.