Advisory Committee Chair
Elizabeth Gardner
Advisory Committee Members
Harvey Hou
Jason Linville
Document Type
Thesis
Date of Award
1-1-2025
Degree Name by School
Master of Science in Forensic Science (MSFS) College of Arts and Sciences
Abstract
Accurate estimation of the postmortem interval (PMI) is a critical aspect of forensic investigations, aiding in time-of-death determination. This study employs High-Performance Liquid Chromatography Mass Spectroscopy (HPLCMS) and Gas Chromatography-Mass Spectrometry (GC-MS) to analyze postmortem metabolic changes and identify potential biomarkers for PMI estimation analyses through metabolomics. Blood serum samples from ante mortem samples (AMS) and postmortem samples (PMS) were categorized into Control (0 hrs), Early PMI (25–58 hrs), and Late PMI (92–163 hrs) groups. Multivariate statistical analyses, including Partial Least Squares-Discriminant Analysis (PLS-DA), Variable Importance in Projection (VIP) scoring, and metabolic pathway evaluations, were conducted to assess biochemical alterations over time. HPLC analysis revealed that adenosine diphosphate (ADP), lactate and citrate were observed in control samples but declined postmortem due to ATP depletion and metabolic degradation. Lactate showed an irregular trend. Amino acids such as isoleucine, methionine, and phenylalanine increased in early PMI, indicating proteolysis, while glycocholate and creatine levels were elevated in late PMI, signifying lipid and muscle degradation. GC-MS further identified ten key metabolites, including L-Proline, L-Leucine, L-Methionine, L-Alanine, and Lactic Acid, as critical indicators of metabolic progression. Lactic Acid and Threonine were predominant in early PMI, while L-Proline, L-Leucine, L-Alanine and L-Methionine exhibited significant increases in late PMI. Palmitelaidic acid, Palmitic acid, Linoleic acid, and Stearic acid were only found in GCMS. These findings confirm systematic postmortem metabolic shifts, identifying key metabolites as potential PMI biomarkers. Lactate and Lactic acid follow same metabolic path yet have different trend in HPLC and GCMS which require further analysis. Despite promising results, limitations like small sample size and lack of validated standards highlight the need for further research. Future studies should integrate a larger sample size and improve statical analysis to enhance PMI estimation accuracy, strengthening the forensic applicability of metabolomics.
Recommended Citation
Chitla, Nishitha Reddy Nishitha, "Analysing Post-Mortem Interval By Blood Metabolomics" (2025). All ETDs from UAB. 6827.
https://digitalcommons.library.uab.edu/etd-collection/6827
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