Postmortem Interval (PMI)
Definition
The elapsed time since death. Entomological PMI estimation uses the developmental stage and known growth rates of insects colonising the body to set a minimum bound on how long ago death occurred.
- What it measures
- Time elapsed from death to body examination
- Entomological role
- Insect age and succession stage provide a minimum PMI estimate
- Actual vs. estimated
- True PMI always equals or exceeds the entomological estimate
Common questions
What is the postmortem interval (PMI)?+
PMI is the elapsed time between death and when the body is examined. Investigators use it to establish the death timeline. Entomologists estimate PMI using insect developmental stages and growth rates to set a minimum bound on how long ago death occurred.
Why is PMI important in forensic investigation?+
PMI helps establish when death occurred, which is central to death investigation timelines. Since entomological estimates can only provide a minimum PMI (the actual PMI may be longer), establishing accurate insect colonization events is essential to interpreting the evidence.
Can insects give us the exact time of death?+
No. Insects provide a minimum PMI estimate based on their developmental stage and succession on the body. The actual time of death could be equal to or longer than the entomological estimate, so other investigative sources are needed to narrow the window.
Related terms
- Accumulated Degree Hours/days (ADH/ADD)
- A temperature-corrected measure of thermal energy available for insect development, calculated by summing the degrees above a species-specific base temperature over time....
- Access Interval
- Any period after death during which insects could not reach the body, whether through concealment, refrigeration, submersion, or wrapping. The access interval...
- Autolysis
- Self-digestion of cells after death caused by the release of lysosomal enzymes. No microbial involvement is required. Autolysis begins within minutes of...
- Cadaveric Decomposition Island (CDI)
- The patch of soil beneath and around a decomposing body, enriched in nitrogen, phosphorus, and organic compounds from decomposition fluids. CDI chemistry...
- Carrion Succession
- The predictable, roughly sequential replacement of insect communities on a decomposing body, driven by changing chemical substrate. Not a strict relay with...
- Colonisation
- The event when gravid female blow flies (or other pioneer species) locate the body and deposit eggs or first-instar larvae. The entomological...
- Entomotoxicology
- The analysis of insect tissue for drugs and toxins when decomposition has made conventional biological fluids unavailable. Blow-fly larvae feeding on a...
- Forensic Entomology
- The application of insect biology to legal investigations, most commonly using the developmental stage and species of insects colonising human remains to...
- Larval Age Method
- Estimating mPMI by identifying the oldest, most developed insect stage present, staging it against a developmental timeline corrected for local temperature, and...
- Minimum PMI (Period of Insect Activity)
- The elapsed time since the first insects colonised the body. Because access may have been delayed, this is a lower bound on...
- Minimum Postmortem Interval (minPMI)
- The earliest point at which death could have occurred, as calculated from insect evidence. The word minimum matters because unknown delays in...
- Putrefaction
- Decomposition of tissues by microorganisms, principally anaerobic bacteria from the gastrointestinal tract. Products include hydrogen sulphide, methane, ammonia, and putrescine, which cause...
Explained in these topics
- Decomposition Stages and the Cadaver as a HabitatThe elapsed time since death. Entomological PMI estimation uses the developmental stage and known growth rates of insects colonising the body to set a minimum...
- Estimating the Postmortem Interval: PrinciplesThe elapsed time between the moment of death and the moment the body is examined. This is what investigators want to know, and it is always equal to or longer...
- Introduction and Scope of Forensic EntomologyThe time elapsed between death and the examination of remains. Insects provide a minimum PMI estimate based on the age and succession stage of the arthropod co...