THE RECOVERY AND ANALYSIS OF DNA FROM FIRED CARTRIDGE CASINGSbyAlicya Orlando Firearms, particularly handguns, are used in the commission of various crimes in the United States, though frequently the only evidence that a gun was used is cartridge casings. Thus, deeper investigation of the utility of DNA analysis for fired cartridge casings has been attempted. Previous studies have explored the probability of developing latent fingerprints and generating STR profiles from unfired and fired cartridge casings in attempt to identify the individual who loaded the gun. In each of these instances casings were washed to remove DNA from prior handlers. In reality, however, criminals will not wash the cartridges before firing them, thus the primary focus of this study was utilizing un-cleaned casings. A cumulative swabbing method was compared to a single swabbing method to determine which generated higher DNA yields and more complete STR profiles consistent with the loader. A consensus method for determining STR profiles was also compared to the two swabbing methods. Thirty volunteers handled 10 cartridges each and loaded them into the magazine of a gun; cartridges were fired and casings were collected and swabbed. DNAs were extracted, quantified, and amplified for STR typing. There was no difference in DNA yield between the swabbing methods, though cumulatively swabbing resulted in the greatest percentages of consistent alleles and profiles. The consensus profiling method had a higher rate of consistency than the single swabbing method but did not outperform the cumulative swabbing method.
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