Soil forensics: How far can soil clay analysis distinguish between soil vestiges?

Area of Science:

• Forensic Science
• Soil Science
• Geochemistry

Background:

• Soil traces are valuable forensic evidence, linking individuals and objects to crime scenes.
• The clay fraction of soil possesses unique signatures, making it reliable for forensic analysis.

Purpose of the Study:

• To determine if soil clay fractions alone can distinguish soil types.
• To assess if soil samples can be differentiated based on collection distance.
• To evaluate the effectiveness of hyperspectral imaging (HSI) and X-ray diffraction (XRD) in soil forensics.

Main Methods:

• Collected Oxisol and Inceptisol samples at varying distances (2m to 1000m).
• Extracted clay fractions for analysis using HSI, XRD, and elemental composition (iron oxides, kaolinite, gibbsite).
• Applied multivariate analysis to the collected data.

Main Results:

• Distinguished between soil types with 65% to 100% effectiveness.
• Successfully differentiated soil samples based on collection distance (10m for Inceptisol, 1000m for Oxisol).
• Clay color and XRD analysis were the most discriminating techniques.

Conclusions:

• Soil clay analysis is a promising forensic tool.
• Routine soil science analytical techniques are effective for forensic soil characterization.
• Clay fraction analysis reliably distinguishes soil types and samples by spatial origin.