Illicit drug distribution: Evaluation of DNA transfer between ziplock bags and capsules

Powders containing illicit substances are frequently poured into capsules and then distributed in small bags to users, often via intermediaries. We report on the transfer of DNA between individuals involved in making, packing, and transporting capsules within ziplock bags (ZLB) via two pathways, each using 10 ZLBs. A two-person chain was created where participant A made and packed the capsules into ZLBs and participant C then carried the bags for four days. A three-person chain was devised where participant A made the capsules, participant B placed the capsules in bags, and participant C carried the bags. The ZLBs were sampled for DNA on the inside, the inner semi-protected portion of the opening, and the outside surface. The exterior of capsules were also sampled along with a storage container. DNA profiling using Verifiler™ Plus was performed with data deconvoluted by STRmix™. Informative DNA profiles were obtained from capsules despite evidence of DNA transfer from the capsules to both storage containers and the inside of the ZLB. The outside of ZLBs yielded complex mixtures, however, the inside of the bag and the exterior of capsules, which had greater protection, yielded profiles with predominately only one to two contributors. This highlights that the inside of the bags and exterior of capsules could be targeted to identify individuals involved in the early packaging stages of the illicit drug pathway while the outside provided more information on recent handling.