PMI determination of human skeletal remains using non-destructive techniques

In the field of forensic analysis, there is a great demand to objectively determine the post-mortem interval (PMI) when human skeletal remains are discovered. Until now, a whole range of techniques have been used to establish the approximate time that has elapsed since the death of the individual, but they have significant drawbacks in terms of reliability and accuracy: they provide an approximate interval but not an exact date; these are relatively invasive techniques, which require staining or removing part of the bone, etc.

“The purpose of this research was precisely to propose a method capable of determining the relatively precise post-mortem interval in human remains using non-destructive measurements,” said Luis Bartolomé, technician of the SGIker Central Analysis Service (SCAB) of the UPV/EHU.

Thus, “we analyzed a set of 53 real human skeletal remains with a known post-mortem interval provided by the Department of Forensic Medicine, Toxicology and Physical Anthropology of the University of Granada. Using real samples for the first time, we built and validated a model by combining two non-destructive tools: Raman spectroscopy and chemometrics”, explains the author of the article.

“Raman spectra, continues Bartolomé, contain physico-chemical information on almost all the components of the sample; however, due to their complexity, in most cases it is not possible to differentiate all the information they contain. Chemometrics is able to extract the parameters of interest from the spectra using mathematical and statistical methods.

“By combining the two techniques, we were able to build a model in which the Raman spectrum of each set of skeletal remains analyzed is associated with a post-mortem interval. Linking the spectrum to a time interval is not an easy task and for this we have used statistical models and logarithms that allow us to link each spectrum to a time. So when we receive human skeletal remains for which we don’t know the time since death, what we do is an interpolation by inserting that data into the validated model, and thus a relatively precision can be obtained,” explained Bartolomé. “The data recorded in the developed model provides valuable, potentially useful and versatile information,” he pointed out.

According to the UPV/EHU researcher, “the combination of the two techniques is a significant advance for forensic medicine and anthropology. However, there is always room for improvement because these types of models perform better the more samples there are and the more variety they have; the model includes more heterogeneity and responds more robustly to a wider range of cases.

– This press release was originally published on the website of the University of the Basque Country

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