An Improved Equation forTBSandADD: Establishing a Reliable Postmortem Interval Framework for Casework and Experimental Studies

Abstract

Megyesi et al.'s (J Forensic Sci, 2005, 50, 618) paper was important to forensic anthropology as it introduced a quantitative framework for estimating time since death in human cadavers, based upon physical appearance by way of scoring on a novel scale. However, errors concerning rounding, temperature scale, and incorrect use of a statistical regression model render their predictive formula unusable. Based upon only their more reliable data, a more appropriate regression model to predict accumulated degree days (ADD) from total body score (TBS) is presented. The new model is also a superior fit (r(2) = 0.91) and produces markedly narrower confidence intervals than the original, which also allowed impossible, negative ADD values. Explanations of the shortcomings in the original analysis and calculations are presented, which it is hoped will help forensic scientists avoid making similar mistakes.

A field study to evaluate PMI estimation methods for advanced decomposition stages

“…On day 12, a maximum difference of 13 points was reached (minimum 18, maximum 32). Using the improved equation for TBS and accumulated degree days provided by Moffat et al [44], days postmortem (dpm) were calculated. This resulted in estimations of 17.9 dpm (95% CI limits 8.2-40.2 dpm) and 305.1 dpm (95% CI limits 124.9-933.5 dpm), respectively.…”

A comparative in situ decomposition study using still born piglets and leaf litter from a deciduous forest

“…Therefore, future decomposition investigations should include comprehensive study designs and analyses and consider: various animal models of different sizes and ages relative to nutrient load and composition; study animals of similar age and size in different in situ soils and local climates; effects of cadaver/surrogate storage (freezing); parallel profiling of the cadaver/taphonomic proxy microbiome and gravesoil microbiota; soil nutrient analysis; gaseous and volatile organic carbon emissions; and volatile fatty acid profiling relative to soil pH. All of these must be implemented parallel to both affordable microbial community profiling techniques and more high-throughput platforms such as NGS.Also, although not implemented in the current study, our future subsurface work entails analysis of the decomposition stages by monitoring physical changes of[41], and total body score[42] determinations for, decomposing mammalian taphonomic proxies. Furthermore, as illustrated by some emerging but aboveground studies[43], innovative experimental designs are required to elucidate microbiome-insect interactions (re chemical signals) in belowground decomposition scenarios, including in the presence of plant litter[44].…”

Karkas Mikrolokasyonunun Postmortem Değişiklikler ve Karkas Dekompozisyonu Üzerine Etkisi

“…TBS to quantify postmortem changes was expressed in points depending on the decomposition rate, and has been previously described [7,8] . The head and neck (0-12), trunk (0-11) and limbs (0-9) were separately scored.…”

“…In order for postmortem changes on the carcasses to be compared and used for determining PMI, total body score (TBS) is used to quantify changes in carcass decomposition. Many authors have studied the relationship between TBS and accumulated degree days (ADD) with the aim of making a more precise and more reliable determination of PMI [1,[6][7][8] . Many authors have examined environmental influences such as temperature and humidity, the impact of physical-chemical agents, the presence of clothing on the body, and the role of insects on the speed of postmortem changes to determine PMI [9][10][11] .…”