Ultraviolet luminescence from latent fingerprints

Area of Science:

• Forensic Science
• Analytical Chemistry
• Optics

Background:

• Latent fingerprint detection on porous surfaces like paper remains challenging.
• Traditional methods often have limited sensitivity and success rates.

Purpose of the Study:

• To evaluate the efficacy of 266-nm Nd:YAG laser-induced ultraviolet fluorescence for latent fingerprint detection on white paper.
• To compare this method with argon-ion laser-based detection.

Main Methods:

• Latent fingerprints from 34 individuals were illuminated using a 266-nm Nd:YAG laser.
• Ultraviolet fluorescence images were captured photographically.
• Fingerprint detection rates were compared with those obtained using an argon-ion laser (514 nm).
• The impact of prolonged UV exposure on fluorescence and subsequent chemical treatments (1,8-diazafluoren-9-one, ninhydrin) was assessed.

Main Results:

• The 266-nm Nd:YAG laser method yielded a 69% detection rate for latent fingerprints on white paper.
• This significantly outperformed the 23% detection rate achieved with an argon-ion laser at 514 nm.
• Prolonged UV exposure reduced inherent fluorescence but did not interfere with subsequent chemical treatments.

Conclusions:

• 266-nm Nd:YAG laser-induced ultraviolet fluorescence is a highly effective technique for visualizing latent fingerprints on white paper.
• This laser-based method offers superior detection rates compared to visible light laser methods.
• The technique is compatible with standard fingerprint development reagents, enhancing its practical forensic application.