The forensic educational outreach initiative - Bridging the gap between education and workplace.

Skills and knowledge gaps frequently exist between forensic educational programs and practical forensic laboratory needs. An educational outreach project involving three post-secondary academic institutions and a large multidisciplinary forensic laboratory was created to provide lectures to students, enable mentorship with forensic scientists, and provide an interactive experience within the forensic laboratory. Mentorship mixer exercises encouraged meaningful interactions between students and scientists, creating opportunities for practical discussion on employment requirements, optimal class selections based on students' interests and forensic science requirements, and better understanding of the daily tasks and duties of operational forensic scientists. Feedback from students, professors, and forensic mentors have resulted in program improvements which will inform the educational outreach initiative going forward, including broader community outreach.

Race Differentiation Based on Raman Spectroscopy of Semen Traces for Forensic Purposes.

Several novel methods to determine externally visible characteristics of body fluid donors have been developed in recent years. These tests can help forensic investigators make predictions about the appearance of a suspect or victim, such as their sex, race, hair color, or age. While their potential benefit is undeniable, these methods destroy the physical evidence in the process. Raman spectroscopy has recently been used as a nondestructive technique to test for many of these characteristics. Here, we present the results from a study to determine the race of semen donors. Using Raman spectroscopy and multivariate data analysis, we were able to build a statistical model that accurately identified the race of all 18 semen donors in the calibration data set, as well as seven additional external validation donors. These results demonstrate Raman spectroscopy's potential to differentiate Caucasian and Black semen donors using chemometrics.

Identification of individual red blood cells by Raman microspectroscopy for forensic purposes: in search of a limit of detection.

Traces of body fluids can be present at a variety of crime scenes. It is important that forensic investigators have a reliable and nondestructive method of identifying these traces. Of equal importance is establishing the limitations of any method in use, including its detection limit. We have previously reported on the use of Raman microspectroscopy and multivariate data analysis to identify and differentiate body fluids. While many studies use serial dilutions to establish limits of detection, we utilized a different approach and demonstrated that a single red blood cell is sufficient to be correctly identified as blood. The experimental Raman spectra of individual red blood cells were loaded into the previously reported models for body fluid identification, and all were correctly classified as peripheral blood. These results demonstrate that our model can be used to identify peripheral blood, even if there is only a single red blood cell present. Furthermore, a single red blood cell is 5000× smaller than the amount of peripheral blood required to perform DNA analysis in a modern crime laboratory. This means that if a bloodstain is large enough for DNA analysis, Raman microspectroscopy should be able to make a positive identification. Considering that the sample analysis reported here was carried out with a different instrument, not the one used for the previously reported method development, these results also represent a form of method validation. The model's ability to correctly classify spectra acquired on a different instrumental platform is crucial in preparing it for practical application. Graphical Abstract Peripheral blood is of great interest in forensic sciences. While many tests are available for the identification of peripheral blood at a crime scene, most are presumptive and destructive. Here we present results that show our new, nondestructive method can identify peripheral blood using as little as a single red blood cell.

Race Differentiation by Raman Spectroscopy of a Bloodstain for Forensic Purposes.

Bearing in mind forensic purposes, a nondestructive and rapid method was developed for race differentiation of peripheral blood donors. Blood is an extremely valuable form of evidence in forensic investigations so proper analysis is critical. Because potentially miniscule amounts of blood traces can be found at a crime scene, having a method that is nondestructive, and provides a substantial amount of information about the sample, is ideal. In this study Raman spectroscopy was applied with advanced statistical analysis to discriminate between Caucasian (CA) and African American (AA) donors based on dried peripheral blood traces. Spectra were collected from 20 donors varying in gender and age. Support vector machines-discriminant analysis (SVM-DA) was used for differentiation of the two races. An outer loop subject-wise cross-validation (CV) method evaluated the performance of the SVM classifier for each individual donor from the training data set. The performance of SVM-DA, evaluated by the area under the curve (AUC) metric, showed 83% probability of correct classification for both races, and a specificity and sensitivity of 80%. This preliminary study shows promise for distinguishing between different races of human blood. The method has great potential for real crime scene investigation, providing rapid and reliable results, with no sample preparation, destruction, or consumption.

Sex Determination Based on Raman Spectroscopy of Saliva Traces for Forensic Purposes.

The forensic analysis of body fluids has made great strides in recent years. Body fluids can easily be identified, and DNA analysis can be used to link a stain found at a crime scene to a specific person. When no reference DNA profile is available and the recovered DNA does not yield a match in a database, it would be incredibly useful if the evidence could still provide investigators with useful information. Biocatalytic and immunoassays can be used to determine a donor's sex, race, and other phenotypic characteristics. However, these tests depend on chemical reactions and are destructive to the sample. Here, we used Raman spectroscopy and multivariate data analysis to develop a nondestructive technique that could be used at a crime scene to determine the sex of a saliva donor. Our internally cross-validated classification model correctly identified 44 (92%) of the 48 donors used for model training. Subsequent external validation correctly identified 11 (92%) of the 12 donors saved for testing. This proof-of-concept study demonstrates the value of Raman spectroscopy as a forensic tool, and indicates that it can be used to elucidate phenotypic information about a body fluid donor. Future studies will expand to other body fluids and additional donor characteristics, such as race and age.