HNO3-PCF: A new lossless light microscopy method for forensic diatom drowning analysis.

Area of Science:

• Forensic Science
• Microbiology
• Environmental Science

Background:

• Diatom analysis is crucial in forensic science for drowning determination.
• Existing methods for diatom extraction and analysis vary in efficiency and accuracy.
• Developing a sensitive and reliable diatom-based drowning detection method is essential.

Purpose of the Study:

• To compare five diatom analysis methods for yield and species consistency.
• To develop and validate a novel, highly sensitive diatom forensic method.
• To establish reliable indicators for distinguishing drowned from non-drowned individuals.

Main Methods:

• Comparison of saponification, filtration, nitric acid digestion, and vacuum filtration techniques.
• Development of the lossless light microscopy diatom forensic method (HNO3-PCF).
• Application of the HNO3-PCF method to submerged pig cadavers and human drowning cases.

Main Results:

• Saponification and filtration significantly improved diatom yield.
• The HNO3-PCF method showed no alteration in diatom community composition.
• Lung diatom concentration was the sole reliable indicator of drowning; heart diatom subtraction minimized false positives.

Conclusions:

• The HNO3-PCF method is a sensitive and reliable tool for diatom-based drowning analysis.
• Lung diatom concentration, adjusted for heart values, is a key indicator for drowning determination.
• The method's simplicity and efficiency make it suitable for widespread forensic application.