Forensic geophysics

Forensic geophysics is the study, the search, the localization and the mapping of buried objects or elements beneath the soil or the water, using geophysics tools for legal purposes. There are various geophysical techniques for forensic investigations in which the targets are buried and have different dimensions (from weapons or metallic barrels to human burials and bunkers). Geophysical methods have the potential to aid the search and the recovery of these targets because they can non-destructively and rapidly investigate large areas where a suspect, illegal burial or, in general, a forensic target is hidden in the subsoil. When in the subsurface there is a contrast of physical properties between a target and the material in which it is buried, it is possible to individuate and define precisely the concealing place of the searched target. It is also possible to recognize evidences of human soil occupation or excavation, both recent and older. Forensic geophysics is an evolving technique that is gaining popularity and prestige in law enforcement.^{[citation needed]}

Techniques

The primary technique is examining visual and physical properties. Someone trained in forensic geophysics uses their knowledge of the terrain and physical makeup of the earth to find burial sites, survey an outdoor crime scene, or help law enforcement agencies create topographical maps.

Ground Based Radar (GBR) is used to detect objects buried in the ground. In law enforcement investigations, GBR is utilized to detect objects buried in the ground and reveal ground structure. Large areas can be searched quickly and non-destructively, greatly improving search efficiency and reducing unnecessary excavation operations. Other forensic applications of GBR include detection of buried bodies, graves, caches, as well as cavities both in the ground and in structures. In order to best develop a suitable range of geophysical tools for forensic application, more research is necessary in both field use and software development.^[1]

Ground Penetrating Radar (GPR) employ radar pulses to do underground mapping. GPR uses a high frequency radio signal that is transmitted into the ground. Reflected signals are then returned to the receiver and stored on digital media. The computer measures the time taken for a pulse to travel to and from the target which indicates its depth and location. The reflected signals are interpreted by the system and displayed on the unit's LCD panel.^[2]

Electrical Resistivity Tomography (ERT) is sub-surface imaging from electrical measurements at the surface or by electrodes.^[3]

Magnometers assist in locating bodies by detecting metal such as zippers, jewelry, or buttons^[3]

References

Further reading

Wikimedia Commons has media related to Forensic science.

• Dupras, D., Schultz, J., Wheeler, S. & Williamns, L. 2006. Forensic Recovery of Human Remains: Archaeological Approaches. Taylor & Francis Group Publishers, Boca Raton, Florida, USA, 232pp.
• Jervis, J., Pringle, J.K., Cassella, J.P. & Tuckwell, G.T. (in press). Using soil and groundwater data to understand resistance surveys over a simulated clandestine grave. In: Proceedings of the 2nd International Soils Forensics Conference, Edinburgh, UK, 30 October to 1 November 2007.
• Milsom, J. 2003. Field geophysics. Geological Field Guide Series, 3rd Edition, Wiley, Chichester, UK, 244pp.
• Pringle, J.K., Jervis, R., Cassella, J.P. & Cassidy, N.J. 2008. Time-lapse geophysical investigations over a simulated urban clandestine grave. Journal of Forensic Sciences, in press.