This paper discusses forensic science developments that were made in the field of vibrational spectroscopy between 2020 and 2022, highlighting factors that shape and focus the trajectory of forensic research as well as efforts to develop capabilities such as portable spectroscopy instrumentation and the rapid identification, determining phenotypic characteristics of sample donors, and quantification of illicit substances.
In this critical review, the authors present a discussion of the forensic developments made in the field of vibrational spectroscopy between 2020 and 2022. Due to the COVID-19 pandemic, there has been an unprecedented disruption on a global scale, and the scientific research community is no exception. However, significant research progress has been made in the last two years, despite the unparalleled times that have been faced around the world. Previous reviews on the uses of vibrational spectroscopy have discussed a wide range of topics, from the overall uses of spectroscopy in forensic science to discussions of analyzing specific forms of evidence. In this Review, the authors cover the latest advances in vibrational spectroscopy for forensic purposes. Since 2020, the number of deaths due to overdose has been on the rise, with >100,000 deaths reported at the start of 2022 in the United States, mostly involving synthetic opioids other than methadone (primarily fentanyl). This has afforded a large push for fast and safe methods to identify and quantify illicit substances. Researchers are working to develop the capabilities of portable spectroscopy instrumentation, allowing rapid and confirmatory on-site identification of drug samples, thus allowing the rapid identification of the components within drug samples. To identify and differentiate body fluids, Raman and IR spectroscopies have been widely investigated in the forensic biology field during the last 14 years. The latest research focused on identifying the full capacity of these techniques in biological stain analyses. This includes determining phenotypic characteristics of the donor based on body fluid traces as well as estimating the time since deposition (TSD), differentiating human and animal blood, and differentiating menstrual and peripheral blood. (Published abstract modified)