Proteomic analysis of decedent scalp hair segments exhibiting a postmortem hair root band

Abstract

A postmortem root band (PMRB) is an opaque microscopic band that can be observed near the root area of hairs from a decomposing body. Although PMRB is a recognized phenomenon in the forensic trace evidence community, protein signatures that are associated with PMRB formation are not well understood. To characterize the specific hair proteins affected by PMRB formation, comparative protein profiles of banded and non-banded hair sections were performed via site specific enzymatic digestion followed by nano-flow liquid chromatography tandem-mass spectrometry (nLC-MS/MS). The sequence coverage in banded sections of hair was ~35% less than in non-banded sections of hair, which reduces the confidence in protein identification and indicates that the abundance or integrity of the proteins is compromised. These findings suggest that proteolysis may play a role in the formation of PMRB.