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Neither microscopical hair comparisons nor mitochondrial DNA sequencing alone, or together, constitutes a basis for personal identification. Due to these limitations, a complementary technique to compare questioned and known hair shafts was investigated. Recently, scientists from Lawrence Livermore National Laboratory's Forensic Science Center and other collaborators developed a peptide profiling technique, which can infer nonsynonymous single nucleotide polymorphisms (SNPs) preserved in hair shaft proteins as single amino acid polymorphisms (SAPs). In this study, peptide profiling was evaluated to determine if it can meet forensic expectations when samples are in limited quantities with the possibility that hair samples collected from different areas of a single donor's scalp (i.e., single source) might not exhibit the same SAP profile. The average dissimilarity, percent differences in SAP profiles within each source, ranged from 0% difference to 29%. This pilot study suggests that more work is needed before peptide profiling of hair can be considered for forensic comparisons.

Background: Both duct tape and items retrieved from water are common pieces of evidence in forensic casework. However, there is little research uniting DNA recovery from immersed tape evidence. The goal of this study was to test the effects of submersion duration and initial cellular concentration on the ability to recover DNA and short tandem repeat (STR) profiles from folded duct tape that has been submerged in ocean water for up to 2 weeks (336 h), as well as the ability to recover touch DNA from such evidence. Methods: Strips of duct tape spiked with human cells or latent prints were submerged in the Delaware Bay. Samples were retrieved at specific intervals between 1 and 336 h of immersion in ocean water. After sample retrieval, DNA was extracted from the tape's adhesive surface and processed for STRs. Results:The results indicate that it is possible to recover enough DNA to yield a complete STR profile from folded duct tape that has been submerged in ocean water for up to 336 h, provided that the initial amount of cellular material is sufficient. It is also possible to recover touch DNA from latent prints, with full STR profiles recovered from samples submerged for up to 168 h (1 week). Overall, the durability and adhesive nature of duct tape seem to provide protection to cellular material on its surface while submerged in aqueous environments.

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