Abstract
Due to the influence of many environmental processes, a precise determination of the post-mortem interval (PMI) of skeletal remains is known to be very complicated. Although methods for the investigation of the PMI exist, there still remains much room for improvement. In this study the applicability of infrared (IR) microscopic imaging techniques such as reflection-, ATR- and Raman- microscopic imaging for the estimation of the PMI of human skeletal remains was tested. PMI specific features were identified and visualized by overlaying IR imaging data with morphological tissue structures obtained using light microscopy to differentiate between forensic and archaeological bone samples. ATR and reflection spectra revealed that a more prominent peak at 1042 cm-1 (an indicator for bone mineralization) was observable in archeological bone material when compared with forensic samples. Moreover, in the case of the archaeological bone material, a reduction in the levels of phospholipids, proteins, nucleic acid sugars, complex carbohydrates as well as amorphous or fully hydrated sugars was detectable at (reciprocal wavelengths/energies) between 3000 cm-1 to 2800 cm-1. Raman spectra illustrated a similar picture with less ν2PO43−at 450 cm-1 and ν4PO43− from 590 cm-1 to 584 cm-1, amide III at 1272 cm-1 and protein CH2 deformation at 1446 cm-1 in archeological bone material/samples/sources. A semi-quantitative determination of various distributions of biomolecules by chemi-maps of reflection- and ATR- methods revealed that there were less carbohydrates and complex carbohydrates as well as amorphous or fully hydrated sugars in archaeological samples compared with forensic bone samples. Raman- microscopic imaging data showed a reduction in B-type carbonate and protein α-helices after a PMI of 3 years. The calculated mineral content ratio and the organic to mineral ratio displayed that the mineral content ratio increases, while the organic to mineral ratio decreases with time. Cluster-analyses of data from Raman microscopic imaging reconstructed histo-anatomical features in comparison to the light microscopic image and finally, by application of principal component analyses (PCA), it was possible to see a clear distinction between forensic and archaeological bone samples. Hence, the spectral characterization of inorganic and organic compounds by the afore mentioned techniques, followed by analyses such as multivariate imaging analysis (MIAs) and principal component analyses (PCA), appear to be suitable for the post mortem interval (PMI) estimation of human skeletal remains.
Highlights
After discovery of skeletonized human remains or individual bones, the most important apprehension for investigators and legal authorities is to distinguish forensic material from archaeological material [1],[2]
Six bone samples with various post-mortem interval (PMI) from approx. 1 to 1000 years as shown in Table 1 were analysed by spectra-analysis, individual chemi-map representations, multivariate imaging analysis (MIAs) and principal component analyses (PCA) (Figs 1 and 2)
MIAs were performed with reflection and Attenuated Total Reflection (ATR) data, but there was no obvious difference in histological structures
Summary
After discovery of skeletonized human remains or individual bones, the most important apprehension for investigators and legal authorities is to distinguish forensic material from archaeological material [1],[2]. PMI estimation usually starts with the macroscopic examination of the bone material, together with the consideration of the gross appearance, tissue preservation and odour. Due to the fact that these features are influenced by many environmental factors (temperature, body size, accessibility for insects or animals, location of the body etc.), which can impinge on the decomposition process, the estimation of the exact PMI is very difficult [3], [4], [5]. Techniques for the investigation of the PMI include microscopic methods [6], [7], [8], chemiluminescence tests, such as the luminol reaction [2],[9],[10], radiocarbon techniques [3, 11], chemical methods, spectroscopical analysis [12], [13], macroscopic UV fluorescence [14] and the detection of various radionuclides [15], [16], [17, 18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
