title: Strategies for potential age dating of fingerprints through the diffusion of sebum molecules on a nonporous surface analyzed using time-of-flight secondary ion mass spectrometry.
abstract: Age dating of fingerprints could have a significant impact in forensic science, as it has the potential to facilitate the judicial process by assessing the relevance of a fingerprint found at a crime scene. However, no method currently exists that can reliably predict the age of a latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (TOF-SIMS) was used to measure the diffusivity of saturated fatty acid molecules from a fingerprint on a silicon wafer. It was found that their diffusion from relatively fresh fingerprints (t ≤ 96 h) could be modeled using an error function, with diffusivities (mm(2)/h) that followed a power function when plotted against molecular weight. The equation x = 0.02t(0.5) was obtained for palmitic acid that could be used to find its position in millimeters (where the concentration is 50% of its initial value or c0/2) as a function of time in hours. The results show that on a clean silicon substrate, the age of a fingerprint (t ≤ 96 h) could reliably be obtained through the extent of diffusion of palmitic acid.
authors.affiliation: National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States.
authors.forename: Shin
authors.initials: S
authors.lastname: Muramoto
authors.affiliation: National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States.
authors.forename: Edward
authors.initials: E
authors.lastname: Sisco
mesh_terms: D003878:Dermatoglyphics; D004058:Diffusion; D044707:Forensic Sciences / Q000379:methods*; D006801:Humans; D019308:Palmitic Acid / Q000737:chemistry; D016062:Porosity; D012629:Sebum / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D018629:Spectrometry, Mass, Secondary Ion; D013499:Surface Properties; D013997:Time Factors
chemical_list: D019308:Palmitic Acid; D012825:Silicon