The PMI (Post-Mortem Interval) for remains of a body enclosed in a plastic bag could best be estimated by blowfly maggot counts.
Blowflies are typically one of the first insects to arrive at a decomposing body, and their life cycle can provide valuable information about the time since death. While other methods such as studying trauma, skeletal evidence, and chemical analysis are useful in forensic investigations, the presence and development of blowfly larvae can give a more immediate estimation of the time since death, especially in cases where the body is concealed or in environments that may limit the effects of environmental decomposition factors.