Many researches document long-term RNA persistence in a variety of tissues and its applicability in estimating the postmortem interval (PMI). Skin-specific mRNA marker, late cornified envelope 1C (LCE1C), was used to identified skin samples. Before using the LCE1C in criminal casework, its persistence and applicability for estimating PMI in different temperatures were tested. Twelve skin samples were collected from 6 patients, and 6 samples were kept at 24°C and others were kept at 40°C for 5 days. The expression levels of LCE1C mRNA are serially detected and quantified using real-time polymerase chain reaction. The expression levels of LCE1C were decreased with increasing the time interval in time-dependent manner, whereas changing the surrounding temperatures did not show any statistical significance. These results could suggest using LCE1C in estimation of PMI. Moreover, these encourage investigators and crime laboratories to know environmental conditions before interpreting the results.