Latent fingerprints, if present, are crucial in identifying the suspect who was at the crime scene. If there are many latent fingerprints or the suspect is from the same household, crime investigators may have difficulty identifying whose latent fingerprints are time-related to the crime. Here, we report changes in the nanoscale topography of latent fingerprints, which may serve as a timeline and could help estimate when the latent fingerprint was imprinted. On the latent fingerprint of an adolescent, we observed a change in nano-topography over time, specifically the formation of nano-chain structures in space between the imprinted papillary ridges. We consequently compared this observation with the decomposition of the latent fingerprints of a child and adult. We observed a significant difference in the time change in nano-topography of latent fingerprints of a child, adolescent, and young adult. The nano-topographical changes of latent fingerprints were studied by atomic force microscopy over 70 days. In the case of child's and adolescent's latent fingerprints, the first nano-chains were observed already 24 hours after imprinting of the latent fingerprint, and the number of nano-chains increased steadily up to 21 days, then we observed that another organic material covered the nano-chains, and they started slowly deteriorating; nevertheless, the nano-chains were still present on the 70th day.
Comment: main article 8 pages, 5 figures without support information