Decomposition of juvenile-sized remains: a macro- and microscopic perspective

Ann H Ross,Amanda R Hale

doi:10.1080/20961790.2018.1489362

Abstract

There is currently a dearth of research investigating the progression and rate of decomposition for juvenile remains. It is thought that juveniles and infants decompose at an increased rate relative to adults due simply to body mass and that skeletal preservation is commonly dependent on intrinsic levels of bone mineral density (BMD). This study investigates the environmental variables important in driving juvenile decomposition as well as examining if currently accepted methodology for quantifying adult decomposition can be applied to juvenile remains. Furthermore, histological analysis is undertaken to test the Histological Index (HI) as a semi-quantitative indicator of decomposition. Thirty-five Sus scrofa ranging between 1.8 and 22.7 kg were deposited to simulate body mass of human infant and juvenile remains. Pigs were deposited every season over two years in the southeastern US with five depositional types: bagged, blanket wrapped, and surface control foetal remains, surface, and buried juvenile remains. Remains were scored quantitatively throughout soft tissue decomposition. Following study completion and skeletonization, a femur was selected from each set of remains for histological analysis. Thick sections were assessed under standard brightfield light and scored using Oxford Histological Index (OHI). Results indicate that seasonal variation is an important factor to consider even when using a standardized time variable such as accumulated degree days (ADD), particularly variation in soil moisture. Soil moisture was a consistent significant variable in the mixed effects model. The pattern of decomposition using total body score (TBS) was similar to that observed by others prior to log transformation with a rapid incline early in decomposition with levelling off. The correlation between time in days, ADD, and TBS was not as strong as those previously reported (R2 = 0.317 and 0.499, respectively) suggesting that TBS as it is currently formulated cannot be directly applied to juvenile remains. Finally, the OHI model performed moderately well, but was variable even within seasons across multiple years.

Highlights

In forensic casework, understanding all stages of decomposition is integral to establishing time-since-death or the postmortem interval (PMI), which with victim identification can inform through exclusion or inclusion of an individual within a missing person’s pool, and increase case resolution [1]
For PMI, the most employed quantitative model is based on a retrospective study of adult remains by Megyesi et al [3] using soft tissue decomposition to score different body regions to arrive at a total body score (TBS) over accumulated degree days (ADD) or the summation of temperature over time [3]
The pattern observed shows the overall fastest rate of decomposition in the summer, followed by the fall season, with spring and winter seasons showing similar ADD values. This does not completely correspond with average temperatures as the fall season has lower average temperatures than the spring season. This pattern does not coincide with relative humidity values with humidity decreasing after the fall season

Summary

Introduction

In forensic casework, understanding all stages of decomposition is integral to establishing time-since-death or the postmortem interval (PMI), which with victim identification can inform through exclusion or inclusion of an individual within a missing person’s pool, and increase case resolution [1]. Estimating PMI is relatively accurate using early soft tissue decompositional changes that typically involve the forensic pathologist evaluating the stages of rigor mortis, livor mortis, and algor mortis to name a few. This is not the case, with the later stages of soft tissue decomposition and postmortem changes to the skeleton due to later taphonomic agents [12, 13]. For PMI, the most employed quantitative model is based on a retrospective study of adult remains by Megyesi et al [3] using soft tissue decomposition to score different body regions to arrive at a total body score (TBS) over accumulated degree days (ADD) or the summation of temperature over time [3]

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