Assessing DNA recovery and profile determination from bloody snow

Abstract

Successful DNA typing of forensically relevant evidence is reliant on both the quality and quantity of biological material recovered from a crime scene. In geographical areas of the world exposed to cold climates, it is not uncommon for biological evidence to encounter a diversity of challenging surfaces and environments, including snowy surfaces. Currently, there is no standard protocol for recovery of bloodstain evidence in snow and very few publications exploring adequate methods of recovering biological evidence from snowy surfaces. In this study, three common substrates (e.g., cotton swabs, FTA paper, and untreated filter paper) utilized by investigators for evidence recovery were evaluated for their ability to recover human blood (DNA) evidence from snow that would be viable for traditional forensic DNA typing. Each biological sample was extracted and quantified to evaluate the quality and quantity of DNA recovered. All samples yielded sufficient non-degraded DNA to proceed with DNA profiling, where complete DNA profiles were generated from each collection substrate. The experimental findings presented herein demonstrate that the ability to recover viable DNA from human blood collected on surface snow is possible using all three collection methods tested.

Keywords: DNA Yield; DNA degradation; DNA recovery; Environmental exposure; Snow.