129-21 Forensic Geophysics: Field Investigation Using Ground Penetrating Radar (GPR) to Search for a Remote, Unmarked Gravesite

Abstract:

This project utilizing Ground Penetrating Radar was developed from a request by a Salt Lake City based investigative reporter seeking help to locate the remains of a victim of Ted Bundy, an American serial killer. The study used the NOGGIN® GPR cart to collect data in grid surveys at a suspected clandestine gravesite located in Sevier County, Utah. 

One major goal of the project was to help provide a form of finality for family members of the victim. Additionally, it provided undergraduate students with valuable experience in planning and executing a real-world GPR survey. Two undergraduate students participated in the planning, surveying, and analysis of the GPR data, with mentoring by faculty/staff from the University of South Florida and Weber State University. They had the opportunity to work with the investigative reporter and better appreciate the significance of geoscience research to the community.

 The Sevier County GPR surveys were conducted over four sites in primarily dry, sandy-silty soils using the NOGGIN® GPR system with a 250 MHz antenna unit. This antenna was chosen because of its ability to produce adequate signal to depths associated with the clandestine burial location, balancing less resolution with greater depth. Initial processing and analysis of radargram line profiles and grids were completed using Reflexw GPR and seismic processing software. Several possible targets were identified as notable diffraction patterns (hyperbolas). One promising shallow target (70-80 cm depth) at Site 4 was later excavated, but turned out to be a large tree root system. 

Data from Sites 1, 2, and 3 were then examined for subtle hyperbolas representing potential targets using newly learned processing workflows in the Sensors & Software EKKO Project V6 R 2.1 Software, recently used in an EarthScope Consortium Instructor Workshop on near-surface geophysics methods. Three isolated targets at depths ranging from 25 cm to 55 cm were identified in several radargram profiles accessed from the software grid view of Site 2. They require further investigation. A cluster of targets was also identified in one line profile (45 - 65 cm depth) which we interpret to be tree roots. No notable targets were identified in the GPR data for either Sites 1 or 3.

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