Post-Mortem Interval (PMI)
Definition
The time elapsed between death and discovery or examination of remains. PMI estimation draws on multiple disciplines: soft tissue decomposition stage, insect succession, skeletal changes, and environmental data. No single biological marker gives a precise PMI alone.
- Primary measure
- Time elapsed between biological death and body examination
- Key indicators
- Algor mortis, livor mortis, rigor mortis, decomposition stage, entomological development, botanical evidence
- Entomology limitation
- Provides minimum PMI only, based on oldest insect developmental stage found
Common questions
What exactly is PMI in forensic work?+
PMI stands for post-mortem interval. It's the time that has passed between when someone died and when their body was examined by a forensic investigator. This is the main piece of information forensic experts work to estimate in death investigations.
Can forensic entomologists pinpoint the exact time of death using insects?+
No. Forensic entomologists calculate a minimum PMI based on how long the oldest insects at the scene have been developing. The actual time of death cannot be earlier than that minimum, but it could have been longer ago. It's one clue among many, not the final answer.
What methods do forensic doctors use to estimate PMI?+
Examiners look at multiple signs: how much the body has cooled (algor mortis), blood pooling patterns (livor mortis), stiffening (rigor mortis), and the stage of decomposition. In some cases, botanical evidence like root growth into remains or pollen layers in grave soil can help narrow down the time 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....
- Forensic Entomology
- The application of insect biology to legal investigations, most commonly using the developmental stage and species of insects colonising human remains to...
- Putrefaction
- Decomposition of tissues by microorganisms, principally anaerobic bacteria from the gastrointestinal tract. Products include hydrogen sulphide, methane, ammonia, and putrescine, which cause...
- 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...
- Adipocere
- A waxy, soap-like substance formed by saponification of body fat under anaerobic, wet, cool-to-moderate conditions. Replaces unsaturated fatty acids with saturated palmitic...
- Algor Mortis
- Postmortem cooling of the body toward ambient temperature, approximately 1-1.5 degrees Celsius per hour under average conditions. Used alongside other postmortem changes...
- Autolysis
- Self-digestion of cells after death caused by the release of lysosomal enzymes. No microbial involvement is required. Autolysis begins within minutes of...
- Calliphoridae
- The blowfly family: metallic-coloured flies that are typically the earliest colonisers of exposed remains. Forensically important genera include Calliphora, Lucilia, Chrysomya, and...
- Carrion Succession
- The predictable, roughly sequential replacement of insect communities on a decomposing body, driven by changing chemical substrate. Not a strict relay with...
- Entomotoxicology
- The analysis of insect tissue for drugs and toxins when decomposition has made conventional biological fluids unavailable. Blow-fly larvae feeding on a...
- Henssge Nomogram
- A graphical method using rectal temperature, ambient temperature and body weight to estimate PMI within a 95 percent confidence interval, with correction...
- Mummification
- Preservation of the body by desiccation rather than liquefaction, occurring when surface evaporation rate exceeds the rate of putrefaction gas production. Common...
Explained in these topics
- Collection of Entomological Evidence at the SceneThe time elapsed between death and discovery of the body. Forensic entomologists estimate the minimum PMI by calculating how long the oldest insects present ha...
- 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...
- Entomological Evidence and Post-Mortem Interval EstimationThe time elapsed between death and the discovery or examination of remains. Forensic entomology typically provides a minimum PMI (the time since first insect c...
- 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...
- Time Since Death: PMI, Henssge Nomogram, Tropical CorrectionThe time elapsed between the moment of biological death and the examination of the body. The directly estimated quantity in TOD work.
- Forensic Entomology Casework and Scene InterpretationThe time elapsed between death and discovery of the body. Entomological PMI estimation gives a minimum PMI based on the developmental age of the oldest insect...
- Forensic Entomology: Insects of Forensic Importance and ApplicationsTime elapsed since death. Entomology gives a minimum PMI (time since first oviposition), not the exact moment of death.
- 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...
- The Medical and Behavioural Forensic SciencesThe time elapsed since death. Estimated using multiple lines of evidence including algor mortis (body cooling), livor mortis (blood pooling), rigor mortis, dec...
- Microbial and Microbiome Evidence in Forensic CasesThe time elapsed between death and the discovery or examination of remains. Accurate PMI estimation is a central goal of forensic decomposition science; the th...
- Post-Mortem Examination, Post-Mortem Changes and Time Since DeathTime elapsed between death and examination. The practical core of forensic-thanatology questions.
- Scope and History of Forensic BotanyThe time elapsed since death. Botanical indicators, including root growth into remains and seasonal pollen layers in grave soil, can help bracket the PMI when...
- Soft Tissue Preservation and Decomposition