Temperature and Time: The Effect(s) Storage Conditions Have on "Touch DNA" Deposited onto Glass Slides

In addition to evidence collection, how evidence is stored can be considered equally, if not even more important. It is necessary to understand what conditions it can be stored in to ensure that it will still be viable for analysis, especially when dealing with trace amounts of biological evidence. About 25 years ago, researchers had discovered that traces of DNA were being left behind on handled items, which is more commonly referred to as “touch DNA”. Since its fairly recent discovery, there is very limited literature that discusses the relationship of evidence storage and touch DNA. In this study, we deposit “charged” latent prints onto a glass slide and use both a digital and a stereomicroscope to visualize the cells left behind. The digital microscope is marketed as the Dino-Lite and uses Diamond™ Nucleic Acid Dye to stain the nucleic acids in the cells, while Trypan Blue dye stains the cytoplasm of dead cells that will be visualized by a stereomicroscope. Once the latent prints are visualized, they are swabbed, extracted, and the DNA is quantified by qPCR. Further analysis of the data will be tracked using graphs to represent any trends or relationships that appear across the varying storage conditions. The ultimate goal is to determine for up to how long and at what temperature touch DNA is still able to be recovered and used for forensic analysis in order to better streamline the process.