Forensic Application of FM-CW and Pulse Radar

Abstract

Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar [Formula: see text] (GPR-X) developed by the U.S. Department of Energy’s Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and [Formula: see text]) (GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled “hot spots.” The [Formula: see text] pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at [Formula: see text] depth. The [Formula: see text] antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the [Formula: see text] antenna was able to penetrate slightly beyond [Formula: see text] beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic-Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.