Evaluation of period since mortality is one of the difficulties in forensic science. Autolysis triggers decomposition, which induces destructive cellular changes causing cell death. Aim: This work aimed to study mRNA expression depending on the process of cell death signaling, to evaluate alterations in antioxidant/oxidant variables and immunohistochemical postmortem changes in rats' livers. Methodology: Thirty-five rats have been classified into 5 groups. The liver was extracted at (0, 3, 6, 12, 24) hours postmortem, to measure the mRNA expression of FasL, PTEN, caspase-3, Bax, and Bcl2 by quantitative PCR in addition to MDA, CAT, GPx, and immunohistochemical postmortem changes. Results: MDA began to rise noticeably after death, CAT began to decline at 3 hours, and GPx declined at 6 hours. At three, six, twelve, and twenty-four hours, the FasL gene's relative expression in the liver of the rats was elevated. However, at twenty-four hours pm, it unexpectedly reduced. Also, the relative expression of the PTEN gene is elevated between three and twelve hours and reduced at twenty-four hours postmortem. Regarding mRNA concentrations of caspase-3 and Bax, a time-dependent increase was observed till twelve hours and a noticeable decline at twenty-four hours. Conversely, the Bcl2 gene's relative expression reduced between three- and twenty-four-hours postmortem. The early postmortem period was positively associated with the relative mRNA expression of FasL, PTEN, caspase-3, and Bax. The early postmortem period has been discovered to have a negative correlation with the relative expression of the Bcl2 gene. Conclusion: These findings supported our preliminary theory, since FasL, PTEN, caspase-3, Bax, and Bcl2 are involved in necrobiosis signaling mechanisms. They are possible candidates for assessing the period since death in 24-hour intervals or fewer. The oxidant/antioxidant and immunohistochemical changes in the liver of rats are also important to estimate the period after mortality. These biochemical indicators can be utilized to determine the early postmortem interval. Keywords: adult albino rats, liver, postmortem interval, FasL, and PTEN.