Background: Latent fingerprints are crucial forensic evidence, but their stability can be affected by environmental factors such as direct sunlight. The findings indicate that prolonged sunlight exposure may be associated with reduced fingerprint quality and forensic usability. Methods: A total of 322 groomed latent fingerprints from one volunteer were deposited on non-porous glass and exposed to direct sunlight for 1–7 weeks. A control sample was preserved without exposure. Fingerprints were developed using magnetic powder and assessed by minutiae counts. Usability was classified according to Slovak forensic standards. Statistical analysis was conducted using the Friedman test and Durbin–Conover test. Results: Significant differences in minutiae counts were observed between the control and selected exposure intervals (weeks 1, 3, 4, 6 and 7; p < 0.05). The degradation pattern was not linear, with initial decreases followed by stabilization in later weeks. Despite statistical differences, 99.38% of fingerprints remained usable for identification, and none were classified as non-usable. Conclusions: Prolonged direct sunlight exposure did not substantially reduce the identificatory value of groomed latent fingerprints on glass. Even after several weeks, most fingerprints retained sufficient ridge detail for personal identification, supporting their evidential relevance in outdoor forensic contexts.
Soták et al. (Thu,) studied this question.