A Forensic Entomology Case Estimating the Minimum Postmortem Interval Using the Distribution of Fly Pupae in Fallow Ground and Maggots with Freezing Injury

Forensic entomology investigates postmortem interval (PMI) estimation using insect evidence. We estimated the minimum PMI of a putrefied male cadaver using pupae in the soil and maggots found in the body. Most of the maggots, collected during the autopsy, were postfeeding third instar larvae with empty crop contents, which developed freezing injuries when the cadaver was placed in the freezer. Pupae in the soil were collected 45 days after the discovery of the body. DNA barcoding revealed that most pupae and maggots were Chrysomya pinguis, with a few exceptions. The minimum PMI was estimated at 10 days before the discovery time based on the scene investigation, maggot developmental stage, distribution of pupae moving away from the body toward pupariation sites, DNA barcoding results, and weather information. To reduce the gap between the minimum and maximum PMI values, complete entomological evidence collection should be conducted at the time of discovery.