Validation Study of the Utility of Using Total Body Score and Accumulated Degree Days to Determine the Post-Mortem Interval of Human Remains From Three Human Decomposition Research Facilities

• NCJ Number: 255132
• Author(s): Joan A. Bytheway; Dawnie Steadman; Daniel Wescott
• Date Published: September 2018
• Length: 27 pages
• Grant Number(s): 2014-DN-BX-K009
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description; Grants and Funding

Annotation

This is the Final Summary Overview of the findings and methodology of a study that sought to validate the Megyesi et al. method for estimating postmortem interval (PMI), which uses total body score (TBS) and accumulated degree days (ADD) to determine the PMI of human remains.

Abstract

In the Megyesi et al. study, crime-scene photos of deceased individuals were observed. Based on the degree of decomposition and applying the physical descriptors from the literature, the deceased was assigned a score for each region of the body (head, trunk, and limbs). The three scores were then totaled (TBS). The TBS was then correlated with accumulated degree days (ADDs). Out of 68 crime-scene photos, 71 percent of the dates of deaths were not known, but they were determined from entomological evidence. The current validation study notes that the use of case photos to assess the postmortem interval is problematic for reasons stated in this report; however, the strength of the Megyesi et al. (2005) study was its use of human subjects, not human analogs, and it made a significant contribution to understanding the human decomposition process with more precision, while providing error rates; however, the method, although having widespread use, has not been validated for its accuracy nor its use in different ecozones. The current study sought to validate the Megyesie et al. method by using cadavers of known date of death; observing cadavers daily through gross observation; taking photos of all regions of the body needed to make an accurate assessment of the TBS; recording accrual daily temperature throughout the study; and comparing TBS scores and known ADDs from three ecozones. The estimated ADDs were produced from the Megyesi et al. equation. Results do not support the accuracy of the TBS/ADD linear regression equation developed by Megyesi et al., because decomposition is not linear. 9 figures and 44 references