UC Davis

Person-of-interest identification is crucial in forensic work, providing probative value for biological evidence obtained from crimes. The emergence of DNA typing as an identification tool has dominated the forensic biology field with DNA’s potential for high statistical weight and ability to discern individuals [1], with current PCR amplification kits containing 20 or more STR loci. Despite the discriminatory power of DNA typing, many cases involve complex evidence due to the presence of mixtures, degraded DNA, environmental PCR inhibitors, and high temperatures affecting the resolving clarity of profiles [1-3, 29, 4, 12]. The emerging field of Forensic Proteomics offers potential due to the more robust chemical properties and abundance of proteins relative to DNA [19, 48]. This study compared the efficacy of individuals’ identification between STR DNA typing and protein profiling using liquid, unstimulated female saliva samples collected from 15 subjects (Samples A1-A15) along with an additional “perpetrator”/reference sample (Sample A16). DNA short-tandem repeat (STR) typing results using real-time qPCR, (RT-qPCR) and capillary electrophoresis were compared to salivary protein profiling results acquired from tandem liquid chromatography-mass spectroscopy (LC-MS/MS) and analyzed with principal component analysis (PCA) was the bases of subject identification with testing occurring 1-3 years after initial sample collection.