A study of the intrinsic variability and the effect of environmental conditions on the formation of a postmortem root band.

A postmortem root band (PMRB) is defined as "an opaque ellipsoidal band composed of a collection of parallel elongated air/gas spaces and is approximately 0.5mm above the root bulb and about 2mm below the skin surface" [1]. It is generally accepted that it can appear in the root of hairs attached to remains during decomposition [1]. This study aimed to investigate the underlying cause and mechanism of PMRB formation. This was done (i) by observing the overall frequency and the intrinsic variability in anagen hairs containing a PMRB collected across five regions of a human decedent's scalp at three time points, and (ii) by determining if PMRB-like features can be induced via immersion in in-vitro controlled environments of anagen hairs plucked from the scalp of a human decedent (ex-situ postmortem hairs) not containing a PMRB. The results of the first objective illustrated that as time since death increased, the frequency of hairs containing a PMRB across the scalp sampling regions increased and the intrinsic variability decreased. The results of the second objective demonstrated that both an aqueous environment and microbial activity are essential for the formation of PMRB-like features. This study was the first to statistically analyze the intrinsic variability of PMRB formation, as well as the first to induce PMRB-like features in roots of ex-situ postmortem hairs.

Differential Scavenging Among Pig, Rabbit, and Human Subjects.

Different animal species have been used as proxies for human remains in decomposition studies for decades, although few studies have sought to validate their use in research aimed at estimating the postmortem interval. This study examines 45 pig, rabbit, and human subjects placed in three seasonal trials at the Anthropology Research Facility. In an earlier paper, we found that overall decomposition trends did vary between species that could be due to differential insect and scavenger behavior. This study specifically examines if scavenger behavior differs by carrion species. Daily photographs, game camera photographs, written observations, and Total Body Score (TBS) documented scavenging and decomposition changes. Results show that raccoons were the most commonly observed vertebrate scavenger, that scavenging was most extensive in winter, and that certain human subjects were preferred over other humans and all non-human subjects. Finally, scavenging activity greatly reduces the accuracy of postmortem interval estimates based on TBS.