FBI Laboratory Surveys on Use of Geophysical Methods

By Michelle Proulx, M.S., and Libby Stern, Ph.D.

A stock image of a metal detector.

Law enforcement may be called upon to search for a buried or obscured target based on an investigative lead, such as disclosure from an informant or cell phone data.

Investigators may use various methods to search for buried targets, including line searches and canine assets, among others. But the use of advanced technology, such as geophysical methods — for instance, metal detectors, ground penetrating radar (GPR), electrical resistivity, and magnetometry — also may help locate a target of interest (e.g., weapons, clandestine grave) at a presumed crime scene. A consensus on best practices for law enforcement deployment of geophysical methods is not yet established.

Most publications on the use of geophysical methods at crime scenes report either: 1) experiments in which a simulated target is buried and the response of an instrument over the target is documented1 or 2) cases of successful detection of a buried law enforcement target.2 Both types of studies are useful for law enforcement agencies considering the use of advanced methods, but neither addresses scenarios in which geophysical methods could not detect a suspected target or the cause of the nondetection.

Survey Participation

To better understand how law enforcement agencies use geophysical methods, including why the technology was unable to detect a suspected target, the FBI Laboratory is conducting three web-based questionnaires to gather information on the use of metal detectors and other geophysical methods to search for hidden or buried targets (e.g., clandestine graves, weapons) in criminal investigations.

These surveys attempt to document:

  1. Types of buried or obscured targets of interest to law enforcement, such as clandestine burials, hidden caches, and buried weapons.
  2. The search environment (e.g., indoors, forest, aquatic).
  3. Kinds of equipment used, such as GPR, magnetometer, and metal detectors.
  4. Acquisition of survey data (e.g., line survey, gridded survey, density of survey lines).
  5. Rationale for inability to detect a suspected target (e.g., target too deep, equipment failure, target not present, wrong settings) and circumstances of successful detections.

If you or any of your contacts have used metal detectors or advanced geophysical methods to aid searches for law enforcement targets, please take the relevant survey(s) and forward this request to your contacts.

The three questionnaires are:

  1. Metal Detector Use in Crime Scene Investigations — Seeking participation from law enforcement personnel or organizations that have used handheld metal detectors in criminal investigations.
  2. Law Enforcement Use of Geophysical Methods — Seeking participation from law enforcement personnel or organizations that have engaged with external experts (e.g., geotechnical firms, academic or government scientists) to conduct geophysical surveys for one or more criminal investigations.
  3. Geophysical Service Providers in Support of Law Enforcement — Seeking participation from individuals (e.g., academic or government scientists, private contractors, and/or law enforcement personnel) who have conducted one or more geophysical surveys for criminal investigations.


All three questionnaires are available at https://le.fbi.gov/lab-surveys. Alternatively, participation in these surveys by phone interview can be scheduled by emailing geophysics@fbi.gov.

These questionnaires are anonymized, and providing personal information is optional. Participation in the questionnaires will close on February 16, 2024.

“Participation in the questionnaires will close on February 16, 2024.”

A photo of an scientist using a metal detector.
A forensic scientist using a ground penetrating radar.
Figure 1: Forensic scientists conducting a metal detecting survey (left) and using a ground penetrating radar (right).

Ms. Proulx and Ms. Stern are researchers in the FBI’s Laboratory Division. They can be contacted at Geophysics@fbi.gov.


1 Jamie K. Pringle et al., “Geophysical Monitoring of Simulated Homicide Burials for Forensic Investigations,” Scientific Reports 10, no. 7544 (2020), https://doi.org/10.1038/s41598-020-64262-3; and Thomas Richardson and Paul N. Cheetham, “The Effectiveness of Geophysical Techniques in Detecting a Range of Buried Metallic Weapons at Various Depths and Orientations,” Geological Society, London, Special Publications 384 (September 2013): 253-266, https://doi.org/10.1144/sp384.18.
2 Alastair Ruffell, Benjamin Rocke, and Neil Powell, “Geoforensic Search to Crime Scene: Remote Sensing, Geophysics, and Dogs," Journal of Forensic Sciences 68, no. 4 (May 2023): 1379-1385, https://doi.org/10.1111/1556-4029.15293.