Uni-Directional PMI Narrowing
Definition
The principle that the TBS formula better constrains the minimum PMI (at least X days must have passed) than the maximum PMI. The upper PMI bound is usually constrained by circumstantial and investigative evidence rather than decomposition score.
- Principle applies to
- Total Body Score (TBS) postmortem interval formula
- Stronger bound
- Minimum PMI (at least X days elapsed)
- Weaker bound
- Maximum PMI, less constrained by decomposition score
- Upper bound source
- Circumstantial and investigative evidence
Common questions
Why can't decomposition scoring pin down the upper limit of PMI as well as the lower limit?+
Decomposition rate variables such as temperature, insect access, and burial slow down or accelerate change unpredictably over longer periods, so once a body has passed a given decomposition stage the score stops distinguishing well between, for example, three weeks and three months.
What kind of evidence typically supplies the missing upper PMI bound?+
Last-known-contact dates, phone or financial activity, mail accumulation, and witness sightings are commonly used to cap the maximum time since death when the biological score alone cannot.
Related terms
- Accumulated Degree Days (ADD)
- The sum of daily mean temperatures above a threshold (usually 0 °C) over a period of interest. Used as a measure of...
- Autolysis
- Self-digestion of cells after death caused by the release of lysosomal enzymes. No microbial involvement is required. Autolysis begins within minutes of...
- Behrensmeyer Weathering Stages
- A six-stage (0-5) macroscopic scale for characterising the degree of environmental weathering on bone, published by Anna Kay Behrensmeyer in Paleobiology (1978)....
- Cadaver Decomposition Island (CDI)
- The localised area of soil and vegetation altered by the decomposition fluids and gases released from a body. A CDI has a...
- Maggot Mass Temperature
- The elevated temperature (10 to 15°C above ambient) generated by metabolic heat from dense aggregations of blowfly larvae on a decomposing body....
- Microclimate Offset
- A temperature correction applied to weather station data to account for the thermal environment at the actual deposition site: shade, building enclosure,...
- Mummification
- Preservation of the body by desiccation rather than liquefaction, occurring when surface evaporation rate exceeds the rate of putrefaction gas production. Common...
- Putrefaction
- Decomposition of tissues by microorganisms, principally anaerobic bacteria from the gastrointestinal tract. Products include hydrogen sulphide, methane, ammonia, and putrescine, which cause...
- Total Body Score (TBS)
- The Megyesi 2005 composite decomposition scoring system: head/neck (1-12) + trunk (1-12) + limbs (1-10), summed to give a score of 3...