Study: Scientists developed a new method for identifying criminals’ movements

Using chemical analysis of soil and dust found on equipment, clothing, and automobiles, scientists developed a new method for identifying criminals’ movements.

This locating system, which was presented as a Keynote Lecture at the Goldschmidt Geochemistry Conference, enables police and security services to compare soil remnants found on personal items to regional soil samples in order to either implicate or eliminate a crime scene’s presence.

Dr Patrice de Caritat, Principal Research Scientist at Geoscience Australia, the government-funded geoscience organisation in Australia, stated, “We’ve conducted preliminary tests to determine whether geochemical analysis can help narrow down a search area. We divided a 260-square-kilometer area of North Canberra into cells (squares) measuring 1 km x 1 km and sampled the soil in each cell. We were then given three samples from the survey area and asked to identify the grid cells from which they originated. This was a ‘blind’ experiment; that is, we were unaware of the source of the samples until the experiment concluded. By comparison, Manhattan Island is approximately 60 km2, indicating that we examined a sizable area.”

They were able to eliminate 60% of the territory under investigation using these methods.

According to Dr de Caritat, “Because much of forensics is about elimination, being able to rule out 60% of an area contributes significantly to successfully locating a sample. You can cut down on the time, risk, and expense associated with the ongoing investigation. The more parameters that we examine, the more precise the system becomes. We have achieved 90% detection in some instances, but believe that would require far too many factors for real-world crime detection.”

The team compared the three blind samples to previously collected samples using a variety of analytical instruments, including Fourier Transform Infrared Spectroscopy, X-Ray Fluorescence, Magnetic Susceptibility, and Mass Spectrometry.

Dr Patrice de Caritat, Principal Research Scientist at Geoscience Australia, Australia’s public sector geoscience organisation, said, “We’ve done the first trials to see if geochemical analysis could narrow down a search area. We took a 260 km2 area of North Canberra and divided it into cells (squares) of 1 km x 1 km, and sampled the soil in each cell. We were then given 3 samples from within the survey area and asked to identify which grid cells they came from. This was a ‘blind’ experiment, in other words, we did not know where the samples came from until the end of the experiment. For comparison, Manhattan Island is around 60 km2, so that shows that we looked at a pretty big area.”

“In Australia, conventional soil analysis has been used to identify and prosecute criminals. For instance, soil analysis was used to track a man who committed a sexual assault on a young girl in Adelaide. There are numerous examples of this type. We now wish to advance this “According to Dr de Caritat.

Dr de Caritat worked with the Australian Federal Police in 2017-18, assisting them in developing their capability for forensic soil analysis.

“Geoscience Australia is now collaborating with the Australian Federal Police, the University of Adelaide, Flinders University, and the University of Canberra on a Defence Department project to incorporate environmental DNA (from indigenous plants, for example) and X-Ray Diffraction mineralogy into the soil and dust location system,” he explained.

Professor Jennifer McKinley (Queen’s University, Belfast) commented, “The revolutionary aspect of Dr de Caritat’s work is that it integrates robust compositional data analysis of multivariate geochemical data into forensic geoscience and applies it in a novel way to forensic soil provenance.”

source: ANI

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