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Novel Quantitative Microscopy of Wet-Powdered Latent Fingermarks of Different Ages

NCJ Number
Minami Yoda, Ph.D.
Date Published
December 2020
13 pages

This project report analyses the effectiveness of novel fingerprint enhancement and illumination methods, with the goals of establishing protocols that would optimize the efficiency of fingerprint detection by improving the detection and yield of latent fingerprints.


The author reports on a research project with the two objectives of determining whether evanescent-wave (TIR) illumination can be used to quantify the characteristics of latent fingerprints, including aged fingerprints, and developing a base understanding of how latent fingermarks interact with a variety of treatments used for their enhancement. The author developed and tested a novel wet-powdering method using commercially available 0.5 μm diameter polystyrene (PS) particles suspended in an acidic (pH 4.1) solution, as well as a novel illumination method for imaging the enhanced fingerprints. The novel illumination method eliminates the background of the image by visualizing only the secretions deposited by the friction ridges of the fingerprint. Fingerprints acquired with that method were quantitatively shown to be more consistent than manually acquired fingerprints. Research findings suggest that PS enhancement gave the best results for sebum-enriched (SE) fingerprints from the first of three test subjects, and PS particle enhancement appears to be capable of enhancing very old SE fingerprints, with no significant changes in the number of matched minutiae for fingerprints aged up to 435 days. The author states that quantitative comparison of how various types of enhancement and illumination affect fingerprints could significantly improve detection and yield of latent fingerprints, and lead to protocols that would optimize the efficiency of their detection.