PrePrint - Influence of Surface Material, Cleaning Frequency and Swab Type on Touch DNA Recovery from Entrance Door Handles: A Simulated Study

This study investigates how surface type, cleaning frequency, swab material, and transfer mode affect Touch DNA recovery from door handles. Using 240 samples across brass, stainless steel, plastic, and wood surfaces, results show that IsoHelix® swabs recovered 2–3× more DNA than rayon swabs. Wood and plastic yielded the most DNA, while brass showed the least. Frequent cleaning reduced DNA recovery and increased background contamination. The last handler was the dominant contributor in 49–74% of samples, depending on material. These findings reveal that DNA recovery is shaped by the interplay of surface properties, hygiene, and sampling tools, emphasizing the need for context-specific strategies and careful interpretation in trace DNA casework.