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Touch DNA Collection Versus Firearm Fingerprinting: Comparing Evidence Production and Identification Outcomes


  • Samuel Nunn Ph.D.

    Corresponding author
    • School of Public and Environmental Affair (SPEA), Center for Criminal Justice Research (CCJR), Indiana University – Purdue University Indianapolis, Indianapolis, IN
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  • Funded by 2010 local research partner grant award from the U.S. Attorney's Office, Southern District of Indiana Project Safe Neighborhoods to the Indiana University Public Policy Institute and Center for Criminal Justice Research.

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Samuel Nunn, Ph.D.

Professor, School of Public and Environmental Affair (SPEA)

Director, Center for Criminal Justice Research (CCJR)

Indiana University – Purdue University Indianapolis

801 West Michigan Street

Indianapolis, IN 46202-5152



A project by a metropolitan police agency in 2008–2009 had police use touch DNA kits to collect cell samples from seized firearms. To assess outcomes, results of touch DNA swabbing of firearms were compared to fingerprinting firearm evidence. The rationale was that fingerprinting, as the older technology, was the baseline against which to compare touch DNA. But little is known about ways to measure touch DNA productivity compared to fingerprinting. To examine differences between the two requires comparable measurements. Two measures were used: quantity of probative or investigative evidence produced and identification outcomes. When applied to firearms seized within an Indianapolis, IN police district, touch DNA produced a larger volume of evidence than fingerprinting, but identification outcomes for the two methods were equal. Because touch DNA was deployed by police patrol officers, there are implications for firearm forensics and the choice of forensic approaches used by police.