Collecting both fingermarks and DNA traces concurrently is not a novel concept, however, the decision as to which trace to prioritise differs across jurisdictions.  Within Australia and New Zealand, there is not a unified protocol for the collection of both latent fingermarks and DNA traces from porous surfaces, and decisions are made based on costs, time constraints, and contextual cues from each case. However, how the collection of one trace may adversely impact the subsequent recovery of another remains poorly understood. Fingermark development is typically faster and simpler than DNA analysis and is often prioritised within dual‑collection workflows . The most common dual collection studies take a fingermark first approach, utilising the newly developed fingermarks as a target for DNA sampling. While this approach achieves results, many studies have found that the risk of DNA contamination increases with the number of interactions with an item prior to sampling. In the case of the fingermark developing agent 1,2-Indanedione-Zinc (IND-Zn), there is also a time limit to when DNA samples can be taken, as DNA has been shown to break down within seven days of exposure. 

To address the uncertainty surrounding optimal trace recovery order, this study aimed to determine whether collecting DNA using four commonly encountered adhesive tapes  (Scotch® removable poster tape, Scotch® wall-safe tape, Hazpak™ sterile minitapes, and SceneSafe™ sterile minitapes) on three substrates (white copy paper, envelopes, and cardboard) will negatively impact the ridge detail of a fingermark and render it useless for identification, when DNA collection is conducted prior to fingermark visualisation. DNA was extracted using the Applied Biosystems® PrepFiler Express™ Bones, Teeth, and Adhesives Extraction Kit with AutoMate™ Express, and amplified using the Promega® PowerPlex™ 21 system. Fingermarks were visualised with IND-Zn and analysed using the University of Canberra scale for split impressions (one side taped and the other side not taped) . No significant difference in fingermark quality was observed between taped fingermarks and their non-taped counterparts. It was found that using DNA adhesive tapes on paper-like exhibits prior to fingermark development with IND-Zn did not negatively impact the ridge detail for both groomed and natural fingermarks. Whilst some adhesives did damage the surface of the item, the fingermark remained intact, and both DNA and fingermarks were able to be recovered. These findings support the adoption of a DNA-first workflow for porous surface exhibits, allowing practitioners to maximise trace recovery without compromising latent fingermark quality.

Authors

• Araminta Abercromby (Centre for Forensic Science, University of Technology Sydney, Australia)
• Georgina E. Meakin (Centre for Forensic Science, University of Technology Sydney, Australia)
• Xanthe Spindler (Centre for Forensic Science, University of Technology Sydney, Australia)
• Alicia M. Haines (Centre for Forensic Science, University of Technology Sydney, Australia)