Forensic applications of Raman spectroscopy for the in situ analyses of pigments and dyes in ink and paint evidence

Raman spectroscopy has proven to be a very useful tool for the forensic examination of various colored evidence, including its use in identifying pigments and dyes in paint and inks. Because both paint and inks consist of complex heterogeneous matrices, forensic scientists typically use a battery of different tests to characterize them, with each method contributing information that will be evaluated and integrated to produce an overall compositional profile. The contribution of the Raman method for the examination of these types of evidentiary materials will be described as well as the factors, which will show why this technique is suitable for the forensic endeavor. The literature offers abundant examples that show how Raman spectroscopy produces data that provide a very high degree of discrimination between samples, can perform non-destructive microscopical in situ analyses, requires minimal or no sample preparation, and produces data that can be easily stored for database purposes. In this review article, a comprehensive review of the forensic applications of Raman spectroscopy for the characterization, differentiation, comparison, and identification of trace evidence and questioned documents, consisting of paint and ink, respectively, is presented. Copyright (c) 2015 John Wiley & Sons, Ltd.