Quantitative/Statistical Approach to Bullet-to-Firearm Identification with Consecutively Manufactured Barrels

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Efforts to use objective image comparison and bullet scanning technologies to distinguish bullets from consecutively manufactured handgun barrels from two manufacturers gave mixed results. The ability of a technology to reliably distinguish between matching and non-matching bullets, where the non-matching bullets were as close in pattern to the matching ones as is probably possible, would provide evidence that the distinctions could be made ''objectively'', and independently of human eyes. That evidence is identical or very close to what seems to be needed to satisfy Daubert standards. It is fair to say that the FTI IBIS image comparison technology correctly distinguished ... continued below

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Striupaitis, Peter & Gaensslen, R.E. January 30, 2005.

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Efforts to use objective image comparison and bullet scanning technologies to distinguish bullets from consecutively manufactured handgun barrels from two manufacturers gave mixed results. The ability of a technology to reliably distinguish between matching and non-matching bullets, where the non-matching bullets were as close in pattern to the matching ones as is probably possible, would provide evidence that the distinctions could be made ''objectively'', and independently of human eyes. That evidence is identical or very close to what seems to be needed to satisfy Daubert standards. It is fair to say that the FTI IBIS image comparison technology correctly distinguished between all the Springfield barrel bullets, and between most but not all of the HiPoint barrel bullets. In the HiPoint cases that were not distinguished 100% of the time, they would he distinguished correctly at least 83% of the time. These results, although obviously limited to the materials used in the comparisons, provide strong evidence that barrel-to-bullet matching is objectively reliable. The results with SciClops were less compelling. The results do not mean that bullet-to-barrel matching is not objectively reliable--rather, they mean that this version of the particular technology could not quite distinguish between these extremely similar yet different bullets as well as the image comparison technology did. In a number of cases, the numerical results made the correct distinctions, although they were close to one another. It is hard to say from this data that this technology differs in its ability to make distinctions between the manufacturers, because the results are very similar with both. The human examiner results were as expected. We did not expect any misidentifications, and there were not any. It would have been preferable to have a higher return rate, and thus more comparisons in the overall sample. As noted, the ''consecutively manufactured barrel exercise'' has been done before, with the same outcome.

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  • Report No.: IS-5170
  • Grant Number: W-7405-Eng-82
  • DOI: 10.2172/892804 | External Link
  • Office of Scientific & Technical Information Report Number: 892804
  • Archival Resource Key: ark:/67531/metadc883045

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  • January 30, 2005

Added to The UNT Digital Library

  • Sept. 21, 2016, 2:29 a.m.

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  • Nov. 30, 2016, 7:12 p.m.

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Striupaitis, Peter & Gaensslen, R.E. Quantitative/Statistical Approach to Bullet-to-Firearm Identification with Consecutively Manufactured Barrels, report, January 30, 2005; Ames, Iowa. (digital.library.unt.edu/ark:/67531/metadc883045/: accessed August 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.