Combined Atomic Force Microscopy and Raman Spectroscopy Investigation of Fingerprints Detriment upon Liquid Exposure for Forensic Analysis

By employing an original experimental setup combining atomic force microscopy (AFM) and Raman spectroscopy to investigate opaque substrates in a liquid environment, the stability of fingerprints (latent or with synthetic residues) left for several hours in acidic water (mimicking acid rain) is studied. It is shown that, despite the general detriment of the fingerprint after a few hours, persistent residuals are found, showing good morphological stability and a characteristic Raman spectrum, which can be considered reliable proof of the presence of a fingerprint on the investigated surface. These findings demonstrate the importance of combining microscopic and spectroscopic analyses in scientific forensic investigations.