The images of latent fingerprints on white paper were observed, and the clearest image was obtained with excitation at 280 nm. The influence of continuous irradiation on the fluorescence of fingerprints was also measured at the optimal excitation wavelengths. The 330 nm peak was dominant at first, but its intensity waned as the total irradiation time increased. Although the 440 nm peak was weak at first, its intensity increased after continuous laser irradiation. The tunable laser consists of a nanosecond pulsed Nd-YAG laser and an optical parametric oscillator crystal. The fluorescence spectra and images were measured at various excitation wavelengths in the ultraviolet region by the time-resolved fluorescence method. Excitation spectra were measured for two main peaks at approximately 330 and 440 nm. The repetition rate of the laser pulse was 10 Hz, and the time width of the individual pulses was approximately 5 nsec. The intensity of each fluorescence spectrum was normalized by an averaged power value acquired from a laser power meter. The delay time was from 4 to 10 seconds. A fingerprint was pressed on a nonfluorescent quartz slide glass or on high-grade white paper after wiping the forehead or nose with fingers. Before impression, the finger was washed with soap and dried in the air. 5 figures and 12 references