A Forensic Spectroscopic Identification Analysis on Skin Evanescent Trauma by Chemometrics

In contemporary biomedicine, rapid diagnosis and accurate treatment of trauma is a top priority. The skin, as the organ with the most extensive contact with the outside world, is always inevitably and easily scarred when subjected to varying degrees of violence. However, when evanescent trauma occurs, the judgment of trauma becomes quite difficult, especially for closed trauma. Evanescent trauma mainly refers to the postmortem autolysis and corruption of body tissues, which lead to the failure to identify the traumatic state occurring before death using traditional detection techniques. Rapid and accurate identification of trauma and even trauma in the evanescent state plays an important role in the actual forensic examination. There have been few records on the development of quick and accurate models for the recognition and prediction of evanescent trauma on the skin. In this study, a predictive model for rapid identification of evanescent trauma in skin tissue was constructed by combining forensic spectroscopy and chemometrics analysis. Based on the mean spectra, principal component analysis (PCA) and corresponding loading plots, suggested that certain biomolecules, such as proteins and lipid molecules, might be the source of the difference between the control group and trauma group, and furthermore, there was a certain pattern of change of each molecule in the continuation of postmortem time. Partial least squares discriminant analysis (PLS-DA) was then applied to estimate the identification power of the training dataset and the testing dataset. The AUC values were 89.55% and 94.67%. In addition, the AUC values of the fresh-phase trauma recognition model were 100% and 100%, respectively, and the AUC values of the evanescent-phase trauma recognition model were respectively 92.52% and 98.77%. In summary, the combination of forensic spectroscopy and chemometrics completely applies their advantages of rapidity, accuracy, objectivity, high resolution and discriminative power to the study of evanescent trauma identification. Moreover, in judicial reality, the combination of spectroscopy and stoichiometry is also expected to make a huge difference in medical and criminal law applications.