Skin and muscle samples are useful to discriminate individuals as well as their postmortem interval (PMI) in crime scenes and natural or caused disasters. In this study, a simple and fast method based on laser Induced Breakdown Spectroscopy (LIES) has been developed to estimate PMI using swine skeletal muscle samples. Environmental conditions (moisture, temperature, fauna, etc.) having strong influence on the PMI determination were considered. Time-dependent changes in the emission intensity ratio for Mg, Na, H alpha and K were observed, as a result of the variations in their concentration due to chemical reactions in tissues and were correlated with PMI. This relationship, which has not been reported previously in the forensic literature, offers a simple and potentially valuable means of estimating the PMI.