Raman spectroscopy for forensic pen ink investigation: a review

The performance of Raman spectroscopy (RS) has improved in recent years due to the significant advantages of its use in various fields, such as archaeology, medicine, foods, and forensics. An aspect of great relevance in forensic investigation is preserving criminal evidence, and nondestructive techniques for analysis are needed. RS has great potential for characterizing pen inks in questioned documents, and it has even been considered promising for trace intersection and dating investigations. This article reviews the evolution of techniques based on Raman scattering for the identification of pen inks and for their use in the characterization of frauds in documents, compares RS with traditional methods of analysis, and provides data for choosing the most appropriate methodology for ink analysis.