NCJ Number
225607
Journal
Journal of Forensic Sciences Volume: 53 Issue: 6 Dated: November 2008 Pages: 1405-1416
Date Published
November 2008
Length
12 pages
Annotation
This article reports on a 4-month, multitechnique, forensic geophysical study over a simulated, shallow-buried, clandestine grave within a complex, urban heterogeneous environment.
Abstract
Bulk ground resistivity surveys were found to be the optimal technique for locating the clandestine burial site, with the chances of detection improving after 3 months, most likely because of the mobile decomposition products that increased the target size. A RM4 Geoscan resistance meter mounted on a custom-built, twin-probe array on a mobile frame that featured two, 10-cm long, steel probes set 0.5 m apart was used to collect bulk ground resistance data. Acquiring preburial control geophysical datasets provided interpretation confidence in geophysical anomalies due to the grave’s presence rather than to pre-existing site material distributions. Careful data acquisition, processing, integration, and visualization steps significantly improved the chances of detecting a burial. This report suggests that high-resolution, ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) profiles be acquired over suspected resistivity anomalies in order to improve target resolution and gain additional information about likely size, distribution, depth, and likely state of preservation of the burial. A simulated clandestine shallow grave was created within a heterogeneous, made-ground, urban environment; a clothed, plastic resin, human skeleton; animal products; and physiological saline were placed in the grave in anatomically correct positions and then recovered to ground level. A series of repeat (time-lapse), near surface geophysical surveys were undertaken prior to burial to act as a control and then 1 month and 3 months after the burial. The range of geophysical techniques used in distinguishing the grave from surrounding areas included bulk ground resistivity and conductivity, fluxgate gradiometry and high-frequency GPR, soil magnetic susceptibility, ERT, and self-potential (SP). The implementation of each of these techniques is described. 2 tables, 8 figures, and 38 references