Detecting Buried Firearms Using Multiple Geophysical Technologies

• NCJ Number: 227935
• Author(s): John J. Schultz
• Date Published: January 2009
• Length: 176 pages
• Grant Number(s): 2007-DN-BX-K304
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research)
• Award: Detecting Buried Firearms Using Multiple Geophysical Technologies

Annotation

The objective of this research was to improve standard geophysical detection methods used to search for firearms commonly used in crime that have been buried in order to conceal or discard them.

Abstract

Of the five geophysical tools tested - magnetic locator, all-metal detector with 11-inch search coil, advanced digital metal detector with 10.5-inch search coil, ground conductivity meter, and cart mounted GPR unit with 500-Mhz and 800-Mhz antennae - the magnetic locator performed better at detecting the larger firearms at deeper levels; and the all-metal detector performed better at detecting smaller firearms. Once high settings were incorporated, the array of firearms detected was approximately the same between the two tools; however, the magnetic locator was still able to detect the larger firearms at greater depth; for example, four firearms were detected at depths greater than 50 cm with the magnetic locator, compared to only one with the all-metal detector. Although no miscellaneous weapons (blunt or sharp edged items) or assorted scrap metals were detected at a depth greater than 45 cm using the all-metal detector, three miscellaneous weapons and one scrap metal were detected deeper than 45 cm with the magnetic locator under the normal/medium setting. The project buried 32 metallic objects, including 16 different types of firearms that represent various weapon types (revolver, derringer, shotgun, semiautomatic rifle, and pistol); 10 miscellaneous weapons; and 6 pieces of scrap metal. Weapons were buried at 5-cm increments. The study focused on how the type of firearm and their metallic compositions affected detection under ground at various depths, using each of the five geophysical tools tested. Extensive figures and 50 references