The discovery, 30 years ago, that DNA profiles can be generated from "touched" surfaces has had a major impact on the use of DNA in investigations of alleged criminal activities. By broadening the types of objects and surfaces from which useful DNA could be recovered, and by expanding the types of criminal offences for which DNA sampling and analysis could be of assistance, the capacity of the legal fraternity to arbitrate during legal proceedings has strengthened.

However, these advances also brought several challenges. Some practitioners were initially reluctant to accept this discovery, and many laboratories had to adjust their workforce and practices to accommodate an increase in samples and new workflows. Operationally, laboratories faced the need to optimise DNA targeting, collection and recovery methods while also investing in reducing contamination risks. Simultaneously, greater attention was required to understand the dynamics and variables influencing direct and indirect transfer, persistence and prevalence of DNA. The increasing complexity of mixtures encountered added further difficulties. In addition, there remained limited availability of relevant probability data on types of DNA profiles recovered after a wide range of activity level related scenarios hindering activity level evaluations (ALE). Importantly, the field required development of sound methodologies to conduct ALE, training of staff to build expertise and coordinated efforts with the legal community to ensure the appropriate and timely use of these evaluations.

This presentation will provide some reflections on: circumstances associated with the initial discovery; the journey of advancing the knowledge, awareness and utilities of DNA Transfer, Persistence, Prevalence and Recovery (DNA‑TPPR); some relevant current DNA‑TPPR research activities; and aspects requiring further efforts to enhance the utilisations of "touch" related samples.