Estimating the minimum post-mortem interval (PMI-min) is crucial in criminal investigations for identifying victims and the circumstances surrounding their death. Traditional post-mortem indicators are reliable only within the first 48-72 h post-mortem. This study explored forensic entomology as an alternative method for PMI estimation, focusing on three cases in Busan, South Korea. Forensic cases involving insect specimens collected from bodies found in Busan from 2022 were examined. Personal and photographic data were documented, and insect specimens were collected, preserved, and identified based on both their morphological characteristics and DNA sequences. To enhance the estimation accuracy, corrected death scene temperatures were calculated using an electronic thermo-hygrometer and meteorological data, applying both quadratic regression and the Support Vector Machine (SVM) model. The PMI-min was estimated using growth models and developmental data from established studies. Lucilia sericata (Meigen) at different life-cycle stages were discovered in all of the cases, whereas Chrysomya megacephala (Fabricius) was found in only two out of the three cases. In each case, the estimated time of death based on the necrophagous flies differed from the deceased's last known activity by approximately one-two days. These discrepancies may arise from the pre-colonization interval (PCI), a critical but often overlooked factor for accurate PMI-min estimation. Additional factors, including weather conditions, oviposition timing, mixed fly populations, and maggot-generated heat, further contribute to the uncertainty of PMI-min estimates. Future research should integrate these variables and employ advanced technologies such as machine learning to improve the accuracy of these estimates.