An assessment of Raman spectroscopy for the estimation of postmortem interval from skeletonised remains

Abstract

Upon the detection of human remains, the postmortem interval (PMI), which is the time elapsed since death, is one of the most substantial particulars necessitating investigation in forensic case work. Due to the resilient nature of bones, skeletonised remains are more likely to persist during decomposition than other biological tissue, making their examination invaluable in the calculation of PMI. To date, attempts at the development of an accurate method for PMI estimation in the later stages of decomposition have not been successful. In recent times, research on benchtop and portable Raman spectroscopy has demonstrated their potential in the calculation of PMI from skeletal remains, yet, at this point, their application for this purpose has not been established. The present study aimed to optimise the method for the analysis of bone samples collected from pig carcasses with PMI ranging from 12-30 months using benchtop and portable Raman instrumentation, and analyse spectral data of diagenetic patterns in decomposing bone. The present study demonstrated that bone scraping is a more effective solution to problematic fluorescence than chemical bleaching. Furthermore, due to the inability to collect usable data at 785 nm excitation, the research exhibited that testing of bone samples at 1064 nm produced high quality spectral data. Additionally, analysis of femora was preferred over other bone classifications. Results obtained using the optimised parameters demonstrated visual differences in peak intensity in spectra from bones with varying PMI, particularly in amide I and amide III, which exhibited a gradual pattern of decrease in peak size and distortion in shape in some spectra. This is likely related to the reduction of collagen in bone samples as PMI increases. Through the optimisation of Raman spectroscopic analysis of bone samples, the study provides the necessary methodology for the characterisation of diagenetic patterns of decomposing bone and preliminary baseline data on which further research and potentially future forensic case work can rely. The study recognises that further inquiry into the diagenesis of forensically relevant skeletal remains can provide substantial information which is crucial to the design of a reliable technique capable of accurately estimating PMI from bone material within the Hawkesbury region in NSW, and producing evidence that is admissible in courts of law.

Date of Award	2017
Original language	English