Minimum PMI (PMImin)
Definition
The shortest interval consistent with the entomological evidence. In practice this is what entomologists estimate: a floor on elapsed time based on the most developed insects found. The true PMI may exceed PMImin by any amount.
- Definition
- The shortest elapsed time interval consistent with the insect evidence from a death scene
- Key assumption
- Colonisation by insects began at or near the time of death
- What it is based on
- The most developmentally advanced insects recovered from the remains
Common questions
What is the difference between PMImin and the actual PMI?+
PMImin is the minimum elapsed time supported by the insect evidence, giving a floor on how long ago death occurred. The true PMI may be longer because colonisation might have started after death rather than immediately. PMImin is therefore a floor, not the final answer.
Why do entomologists only estimate PMImin?+
Entomologists can only see how developed the insects are. They know death cannot have been much earlier than the most mature insects suggest. But they cannot tell if the first flies arrived right at death or hours later, so they report the minimum interval as their best estimate.
Is PMImin conservative or does it overestimate time since death?+
PMImin is conservative and typically underestimates time since death. It assumes colonisation started at the moment of death, which is the best-case scenario for rapid insect arrival. If colonisation was delayed, the actual death occurred earlier, making the true PMI longer.
Related terms
- Accumulated Degree Hours (ADH)
- A temperature-corrected measure of developmental time. Calculated by summing (hourly ambient temperature minus the species-specific base temperature threshold) across the period of...
- Entomotoxicology
- The analysis of insect tissue for drugs and toxins when decomposition has made conventional biological fluids unavailable. Blow-fly larvae feeding on a...
- Colonisation Interval
- The elapsed time since the first insect colonised the body. Often shorter than the PMI if access was delayed by concealment. An...
- Colonisation Wave
- A discrete succession of insect species arriving and exploiting remains as the decomposition chemistry changes. Blow-flies typically colonise first; flesh flies, beetles,...
- Maggot-Mass Thermogenesis
- The elevation of temperature within a dense larval aggregation by the combined metabolic heat of thousands of larvae. Documented elevations range from...
- Microclimate
- The localised temperature and humidity conditions immediately at the body surface, which often differ from the nearest weather-station record by several degrees....
- Post-Mortem Interval (PMI)
- The time elapsed between death and discovery or examination of remains. PMI estimation draws on multiple disciplines: soft tissue decomposition stage, insect...
- Thermal Bias
- Systematic under- or over-estimation of developmental temperature caused by using distant weather-station data, solar radiation on an exposed body, or micro-environmental features...
Explained in these topics
- Sources of Error and Uncertainty in Entomological PMIThe shortest interval consistent with the entomological evidence. In practice this is what entomologists estimate: a floor on elapsed time based on the most de...
- Forensic Entomology Casework and Scene InterpretationThe earliest possible time of death derived from entomological evidence alone. It assumes colonisation began at or near death; if colonisation was delayed, the...