Investigating the Impact of Hand Sanitizers on Latent Fingerprints When Used with Metronic Poly Mailers

Latent fingerprint analysis remains a cornerstone of forensic identification. With the rise in hand sanitizer use and the growth of online delivery services during the COVID-19 pandemic, concerns have emerged regarding the potential impact of these substances on fingerprint recovery. This study evaluates the effect of four common hand sanitizers (water-based alcohol, gel-based alcohol, Dettol Instant Hand Sanitizer, and a benzalkonium chloride (BAC) non-alcoholic solution) on latent fingerprints deposited on Metronic poly mailers. Additionally, the efficiency of three development techniques—magnetic powder, cyanoacrylate fuming, and a sequential combination of cyanoacrylate fuming followed by magnetic powder—was assessed. Fingerprints from 10 donors were analyzed using the Center for Applied Science and Technology (CAST) grading scale and an Automated Fingerprint Identification System (AFIS). Results revealed that alcohol-based sanitizers significantly diminished fingerprint quality, while the Dettol and BAC formulations paradoxically appeared to enhance ridge clarity. The combined technique (cyanoacrylate fuming and magnetic powder) yielded the highest clarity across most conditions. These findings provide valuable data for forensic protocols when sanitizer contamination is suspected.