Fingermarks are present on a variety of evidence types with the potential to provide identifying information from ridge patterns and the small amount of DNA present. Difficult evidence types such as fired brass cartridge cases present degradation challenges in subsequent DNA, and ridge analysis. Proteins present in the fingermark are robust and likely not as affected by these challenges. Proteomic genotyping is a new and developing field in fingermark analysis which utilises single amino acid polymorphisms (SAPs) within these proteins to infer non-synonymous single nucleotide polymorphisms (SNPs). It promises to offer alternative and/or complimentary identifying evidence to current fingermark analyses. Allowing DNA profiles to be inferred from digested SAP containing peptides, termed genetically variant peptides (GVPs). These GVPs can then be identified in forensic samples with liquid chromatography tandem mass spectrometry (LC-MS/MS). MPS genotyping using nuclear and mitochondrial DNA represents a strong alternative to standard capillary electrophoresis genotyping on degraded samples such as cartridge case fingermarks. The development and optimisation of a DNA/protein co-extraction method has the potential to utilise both these analyses. The aim of this research is to develop a targeted proteomic genotyping workflow for the analysis of a panel of GVPs within a sample utilising the co-extraction of protein/DNA from cartridge case fingermarks. Initial workflows have been developed in myself and Orla Harris’ Masters project for the targeted proteomic genotyping of cartridge case fingermarks and hair respectively. The next steps for further workflow development are the incorporation of synthetic peptide standards, further optimisation in the; extraction/digestion, liquid chromatography method, and mass spectrometry method. Fingermark visualisation reagent/technique compatibility is also an area that will be explored to ensure complementarity with ridge detail analysis performed by the New Zealand Police.

Authors

• Sam McCullough (The University of Auckland, New Zealand)
• Orla Harris (The University of Auckland, New Zealand)
• Margarita Cruz (The University of Auckland, New Zealand)
• Martin Middleditch (The University of Auckland, New Zealand)
• Viji Sarojini (The University of Auckland, New Zealand)
• SallyAnn Harbison (The University of Auckland, New Zealand)