Can microbes on skin help linking persons and crimes?

Abstract

Linking persons to crimes through DNA analysis is a well-established approach for more than 25 years. While enormous numbers of cases all over the world have been solved based on DNA, there is still need for additional tools for improvement in physical evidence choice and collection. Unfortunately not all samples collected from crime scenes, are suitable for linking persons to crimes due to the quantity and quality of the human DNA collected. Recent studies have shown personality of bacterial community on human body surface that may open new perspectives for forensics. The aim of the study was evaluation of variability of bacterial communities on skin of palm and fingers between and within individuals as well as transfer of bacterial DNA during contact to the object and persistence of community parameters during storage. Four volunteers were recruited and samples collected during 5 days and afterwards once per week during 1 month in the morning and in the afternoon by swabbing of palm and fingers after holding sterile object for 1 min with persons dominant hand. The samples were also collected from the handled objects, except the first object, in which surface was quartered and sampled by quarter zone with 1-week interval after storing the object at room temperature. DNA was extracted and metagenomic analysis of bacterial community using 16S rRNA gene hypervariable regions was performed on Roche/454 platform. Our preliminary results are promising however foresee need for more elaborative studies to be able to implement this approach into the routine practice.