Development of latent fingerprint detection based on UV induced fluorescence

Latent fingerprint is one of the important evidences used to identify criminals in criminal cases, so fast and non-destructive detection of latent fingerprints is important. At present, the usual method always preprocess the sample before detecting the latent fingerprints, and it will cause a certain degree of damage to the latent fingerprints. Based on the characteristic that the organic components of latent fingerprints will produce the fluorescence when induced by ultraviolet, a fast, non-destructive and high-contrast detection technique is studied. In this paper, an ultraviolet induced fluorescence detection method based on two-dimensional laser scanning system is proposed to realize the rapid scanning of latent fingerprint area. The experimental parameters are optimized according to the contrast of fingerprint striae, the fingerprint image is reconstructed by image processing. In order to verify the feasibility of this method in practical application, the experiment of detecting the aged latent fingerprints on five kinds of papers deposed for different days is carried out. The detection results show that the aged latent fingerprints deposed for three days can be clearly visualized. For aged latent fingerprints deposed for five days and seven days, the contrast of fingerprint striae is reduced, but the fingerprints can still be distinguished. The method can realize fast, non-destructive and high-contrast detection of latent fingerprints on papers. It can be used in different fields such as criminal investigation and trace detection.