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Background: Time since death (TSD) is an important parameter to the forensic expert. Only a fewer studies are available in the literature to determine the relationship between vitreous K + concentration and TSD especially among injury (trauma) cases and thus information on the same is patchy and scanty. Objective: To determine the relationship between changes in vitreous K+ concentration with increasing TSD among injury (trauma) cases. An additional objective was to derive a formula for determining TSD from changes in levels of vitreous K+ in the study subjects. Materials and Methods: In this study, autopsy cases brought to the mortuary of Department of Forensic Medicine and Toxicology of a tertiary care center, were the subjected for collection of vitreous humor for determination of vitreous potassium. Data of 55 such cases where autopsy confirmed the cause of death as injury (trauma), were included in this study. Determination of potassium level in the collected sample was done using ion-selective electrode method (Biolyte 2000 auto analyzer). Results: A linear relationship was observed between vitreous potassium concentration and TSD in both the eyes. External factors like seasonal variations and temperature, gender difference and age had no appreciable effect on the concentration of vitreous potassium in either eye. In this study, the linear regression equations obtained from potassium concentration (y) verses time (x) for the two groups among injury (trauma) cases were as follows: For right eye: Regression line (y) = -5.040 (x) = +1.989, for left eye: Regression line (y) = -5.223 (x) = +2.005. The potassium levels are found to increase up to 40 h after death. Conclusion: The study highlighted the usefulness of relationship between vitreous potassium concentration and TSD in both the eyes. The formula calculated from the current study could prove to be more appropriate as it is based on a more recent study and more reliable tests. [ABSTRACT FROM AUTHOR]