Affiliation:
1. Department of Physics Politecnico di Milano p.zza Leonardo da Vinci 32 I‐20133 Milan Italy
2. Direzione Centrale per la Polizia Scientifica e la Sicurezza Cibernetica – Servizio Polizia Scientifica Polizia di Stato via Tuscolana 1558 I‐00173 Rome Italy
Abstract
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.