Touch DNA localization and direct PCR: An improved workflow for STR typing from improvise explosive devices

Abstract

Improvised explosive devices (IEDs) are used for terrorism worldwide. Bomb assemblers could leave touch DNA on IED surfaces but most result in low STR typing success rate. Part of this is due to being unable to locate touch DNA on the evidence. In order to solve this problem, we investigated the efficiency of three fluorescent dyes to locate touch DNA on the two IED substrates (PVC pipe and electrical tape). Different areas with high and low touch DNA concentrations were distinguishable. Afterward, the stained samples were amplified by using direct PCR. The results showed that it was possible to obtain a high partial profile from a sample that had been touched for 15–30 s. The developed method (reagent, light source, and direct PCR) has the potential to transform the way forensic scientists work with evidence potentially containing touch DNA.