Spectroscopy Techniques Unveil New Methods for Detecting Forged Documents

Forgeries are designed to deceive the receiving party that a fraudulent document is in fact legitimate. Falsified documents are commonly seen in loan applications, bank documents, and gaming tickets, to name a few (1). To combat this nefarious practice, researchers are looking at ways to use spectroscopy to detect when a document has been falsified.

A recent study from researchers at Istanbul Medeniyet University explored this topic at length. Published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, the research combines spectroscopic techniques with advanced chemometric methods to offer a powerful and cost-effective solution for forensic investigations (2).

Man forging a signature on a legal document, Cheat, document fraud and betrayal. Generated with AI. | Image Credit: © Exnoi - stock.adobe.com

In their study, the research team focused on using spectroscopy and chemometrics to analyze ink samples from ballpoint pen ink. Ballpoint pen inks are commonly used instruments in document forgery, which is why they were used in the study (2). Eleven ink samples from three different brands of black, blue, and red pens were analyzed in this study using ultraviolet-visible (UV–vis) spectroscopy, Fourier transform infrared attenuated total reflectance (ATR FT-IR) spectroscopy, and statistical tools such as principal component analysis (PCA) (2). By using these different techniques, the researchers developed a comprehensive approach to differentiate inks based on their color, brand, and even sub-brand.

In particular, the study demonstrated that ATR FT-IR was effective in identifying different ink brands. What makes this technique good for this purpose was that only a small amount of ink—equivalent to a single letter or number on a document—leaving the rest of the sample intact (2). Meanwhile, UV-vis spectroscopy was good at distinguishing ink colors (2). The study's statistical analyses, including PCA and hierarchical cluster analysis (HCA), reinforced the reliability of these techniques in forensic applications (2).

The study also contained a case study of a falsified old-dated check, where the ATR FT-IR analysis successfully identified the ink and verified the document's authenticity (2). This capability underscores the methodology's potential in real-world forensic scenarios (2).

This study advances forensic analysis in several key ways. First, forensic laboratories with limited resources could benefit from this research. By relying on relatively accessible tools like UV–vis and ATR FT-IR spectroscopies, the proposed methodology provides an affordable yet highly effective solution for document examination (2).

This comes at a time when accessibility of these tools is improving thanks to portable instrumentation. Because of the push from scientists to develop more rapid and portable instruments, researchers have been able to conduct their analysis on-site, removing the need to transport samples to an off-site laboratory (3).

The ability to analyze ink from small sections of documents without compromising the integrity of the evidence is a significant advancement for forensic science. Courts require high standards of evidence, and this methodology ensures that document examination meets rigorous legal criteria (2).

Furthermore, the study's approach could extend beyond ink analysis. By adapting the same principles, forensic experts may explore applications in other areas, such as detecting counterfeit currency, verifying legal documents, or investigating historical artifacts.

By combining UV–vis and ATR FT-IR spectroscopy with robust statistical methods, the study provides a versatile, cost-effective, and highly accurate methodology for detecting forged documents. Spectroscopy is routinely being used in forensic analysis for a variety of applications (4). Apart from document analysis, spectroscopy has been used to analyze bloodstains and body fluids, as well as narcotics and other illicit drugs (4).

This study highlights the growing application of spectroscopy in forensic analysis, a trend expected to continue the rest of the 2020s and beyond.

References

1. Clement, J. L.; Risi, B. Laboratory Examination of Counterfeit and Fraudulently Altered Documents. Int. Crim. Pol. Rev. 1983, 138–163. https://www.ojp.gov/ncjrs/virtual-library/abstracts/laboratory-examination-counterfeit-and-fraudulently-altered#:~:text=Forgeries%20are%20defined%20as%20any,erasure%2C%20scraping%2C%20or%20bleaching.
2. Mirzanli, U.; Guzel, P.; Akbay, N. Spectroscopic Techniques and Chemometrics for Ink Analysis: Document Analysis Application. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2025, 326, 125167. DOI: 10.1016/j.saa.2024.125167
3. Wetzel, W. Portable NIR Spectrometers Enhance Flexibility in Forensic Science. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/portable-nir-spectrometers-enhance-flexibility-in-forensic-science (accessed 2025-01-06).
4. Wetzel, W. Highlights from The Future of Forensic Analysis. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/highlights-from-the-future-of-forensic-analysis (accessed 2025-01-06).