Latent Fingerprint Aging from a Hyperspectral Perspective: First Qualitative Degradation Studies Using UV/VIS Spectroscopy

Latent print age estimation is an important topic in the emerging field of digitized crime scene forensics. While several capturing devices have recently been studied towards this goal, hyperspectral imaging in the UV/VIS (ultraviolet and visible light) range of the electromagnetic spectrum has not been investigated so far. Addressing this research gap, a first qualitative evaluation on the aging behavior of 30 latent print time series from 6 different donors is conducted, utilizing an optical reflection spectrometer. Results show more unpredictable aging tendencies in the ultraviolet spectral range, whereas a general logarithmic trend from prior work (using non-spectral capturing devices) is confirmed for the visible light band. Furthermore, a different behavior of eccrine and sebaceous print components is found, especially in the ultraviolet band, where sebaceous components seem to become reflective to the emitted radiation and might furthermore be utilized for studying longer aging periods in contrast to eccrine prints. Overall, the combined degradation information of the ultraviolet and the visible light band seem to provide the most reliable results for measuring a reproducible aging trend, serving as a potential opportunity to address the strong influence of different sweat compositions on the aging behavior of latent prints.