ABSTRACT
Background: Postmortem interval (PMI) estimation is an important goal in forensic medicine. After death, many physiochemical changes occur in a regular sequence and thanatochemistry is the chemistry of death. They can be used to arrive at an approximate time of death. Aim: to estimate the time since death using a scoring method for three postmortem changes; hypostasis, rigidity and corneal turbidity in sever burn cases. Also, to evaluate the use of thanatochemistry; potassium (K+) in vitreous humor (VH) and serum in determination of (PMI) and compare the accuracy of thanatochemistry and the scoring method for postmortem changes in estimation of PMI. Methods: The study was conducted on 100 adult autopsy cases of known postmortem interval presented to the mortuary of Alexandria from May 2017 to May 2018, 50 burn cases where autopsy confirmed the cause of death as severe burns and another 50 control cases. The development of postmortem rigidity, hypostasis and corneal turbidity was assessed and numerically scored. The potassium (K+) levels in vitreous humor (VH) and serum were measured. The data were statistically analyzed and linear regression analysis was used to obtain equations for calculation of PMI .Results: All the studied variables in the present study were significantly correlated with PMI; highest correlation coefficient in control and burn groups was for K+ level in VH, followed by corneal turbidity and serum K+ then rigidity in burn groups, but in control groups the highest correlation coefficient was for K+ level in VH and serum, followed by rigidity then corneal turbidity and lastly hypostasis. All equations obtained from the present study can predict PMI but with different levels of accuracy. Conclusion: The most accurate equation in control cases was that concerning with all the five studied variables. Furthermore, the scoring method for the physical postmortem changes was proved to be more valuable in PMI estimation than thanatochemistry. No much difference between accuracy of equations in burn cases was that concerning with all the five studied variables.