Temperature & Time: The Effect(s) of Storage Conditions on Touch DNA Deposited onto Drug Baggies

Activity-level propositions in forensic biology address the question “how did the DNA get there,” rather than simply “who’s DNA is it?” DNA transfer, persistence, prevalence and recovery (DNA-TPPR) are key activity-level variables useful in developing the explanations that inform activity-level propositions. In this project, the focus will be looking at these key variables. Present work will use true fingerprints on drug baggies stored at different time intervals and temperatures to define these activity-level variables. In Aim 1, we will change the time since deposition to see the effect on the deposited touch DNA. The different time points are 0, 1, 3, 5, 7, 14, and 21 days. In Aim 2, we will change the temperature to see the effect on the deposited touch DNA. The different temperatures are room temperature and 37℃. Both Aim 1 and 2 will look at cell count and DNA quantity to evaluate the possible changes. The cell count of the samples will be obtained with Diamond Dye and a Dino-Lite or Trypan Blue Stain and a microscope. The DNA quantity of the samples with be obtained through an organic extraction and real-time PCR. The cell count or DNA quantity will be plotted verse the storage length or temperature to determine a relationship. We would expect to define the mean and range of cell count and DNA quantity for these different storage lengths at different temperatures to relate to the key activity-level variables.