This article reports on research designed with three goals in mind: (1) identify how long it would take before an aged female fingerprint could no longer be differentiated from a male fingerprint; (2) identify a correlation between the data collected and a specific time since deposition (TSD) time point; and (3) identify whether a specific amino acid could be contributing to the decreasing response seen for the aging fingerprints.
Past investigations involving fingerprints have revolved heavily around the image of the fingerprint—including the minutiae, scarring, and other distinguishing features—to visually find a match to its originator. Recently, it has been proven that the biochemical composition can be used to determine originator attributes, such as sex, via chemical and enzymatic cascades. Although this provides pertinent information about the originator’s identity, it is not the only piece of information that can be provided. Using ultraviolet–visible (UV–vis) spectroscopy, the current project evaluated aged fingerprints for 12 weeks via three chemical assays previously used for fingerprint analysis—the ninhydrin assay, the Bradford assay, and the Sakaguchi assay. As fingerprints age, the conditions to which they are exposed cause the biochemical composition to decompose. As this occurs, there is less available to be detected by analytical means. This results in a less intense color production and, thus, a lower measured absorbance. The results of the current study afforded the ability to conclude that all three goals set forth for this research were accomplished—a female fingerprint can be differentiated from a male fingerprint for at least 12 weeks; UV–vis data collected from aged fingerprints can be correlated to a TSD range but not necessarily a specific time point; and the decomposition of at least a single amino acid can afford the ability to estimate the TSD of the fingerprint. (publisher abstract modified)