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Welcome back, readers, to the next segment of the forensic use of ground penetrating radar! In our last segment (https://www.sensoft.ca/blog/forensic-use-of-ground-penetrating-radar-casework/), we explained how GPR can be a powerful tool for investigators to use as a sort of “presumptive test” when attempting to locate a clandestine grave or other item buried beneath the soil surface. However, for this tool to be effective within an investigation, the investigator must first understand how to use it and in what circumstances it can and should be used. When approaching the concept of teaching any subject – particularly something as specialized as GPR – it’s important to first understand that not everyone learns the same way; some people learn best by seeing/hearing (such as reading an article or watching a lecture/webinar) and some people learn by doing (such as workshops or hands-on demonstrations). That is why it is so critical to take a well-rounded approach to teaching the techniques and applications of GPR within the forensic sciences.
With the advancement of technology, much of the traditional lecture-based format of education has transitioned to an online, distance education format either in the form of live webinars that utilize real-time instructors or text-based, self-paced training courses. The resources available to help teach investigators the best way to use and apply GPR to medicolegal death investigations are available in various formats. A great example are the webinars (https://www.sensoft.ca/georadar/webinars/) and SensoftU online courses offered by Sensors & Software which are hosted live and available on-demand (http://www.SensoftU.com). These trainings use a combination of auditory and visual education, including filmed demonstrations of the GPR principles and practices they are teaching and offer easy access to various GPR data interpretation and processing topics. Other online-learning platforms present the concepts of GPR application to death scenes in a more traditional academic setting including the UF Master’s Degree in Forensic Medicine which discusses concepts of clandestine grave detection based on geophysics within a graduate-level course.
However, even once theoretical concepts are presented in a lecture-based format, it is very helpful to be able to apply the concepts to a hands-on practical demonstration. This is why field demonstrations, and in-person workshops are a crucial component of providing a comprehensive learning environment to ensure that investigators understand all aspects of the technology they’re using. Simulating an actual field investigation where instructors bury items of evidence (for e.g., skeletal material, evidentiary items, and/or animal carcasses) in mock clandestine graves for students to locate using GPR, provides a real-world scenario in a controlled, instructor-guided learning environment (Figure 1). There is a great deal of planning and logistics to setup these field sites including burying skeletal materials and evidentiary items. The purpose of these scenarios is to simulate the types of actual cases investigators may encounter, so the mock gravesites are dug at relatively shallow depths, usually 2-4 feet. The carcasses or skeletal materials are sometimes wrapped in tarps, plastic sheeting, or other material to simulate body concealment methods.
In a real-world setting, GPR is typically used to locate potential clandestine gravesites using the “pseudo-grid” method first, rather than a complete grid data collection, which is very time consuming. The reason for this is that GPR can be used more as a sort of presumptive test to identify possible clandestine gravesites to flag areas of interest for further investigation with a more detailed grid survey. In addition to GPR, other field techniques are used such as probing and coring to help identify a suspected gravesite (Figure 2). Within the lecture portion, the specific techniques involved in systematically excavating a gravesite are taught, which are then put into practice at the field site. Students are expected to set up a grid around the suspected grave area. The considerations for determining the grid size and placement are scene dependent. That is, they must consider the size of the suspected grave along with any items of evidence that may be present on the surface to ensure their grave encompasses all relevant items that must be included in the mapping, measuring, and excavation process.
Up to this point, the investigation process is driven by the data students are collecting. They will explain to the instructors why they feel they have correctly identified their gravesite based on their GPR use, taphonomic clues, surface evidence, and any other relevant factors. Often, students will learn that not all grave-like anomalies are forensically significant and to only focus time and effort on excavating areas of interest to their investigation (Figure 3).
This practice environment is critical because the instructors know exactly where the gravesites are and can explain to students the differences between the actual gravesites and non-gravesite anomalies so that students can better understand the nuanced differences.
Once students have identified their gravesite using GPR (Figure 4), they excavate their potential gravesites to develop tangible associations between what was shown on the GPR screen and what was found within the suspected grave. It’s much better for students to discover they’re making mistakes and learn to correct them in this environment, rather than on an actual death investigation scene. Providing the opportunity for students to apply what they’ve learned in a lecture-based format, in a hands-on scenario is one of the best methods to bring theoretical concepts into practice.
Story courtesy of PhD. Lerah Sutton, PhD
Director – Forensic Medicine Educational Program
Assistant Director – Maples Center for Forensic Medicine
University of Florida College of Medicine
