A Quantitative Analysis of Torn and Cut Duct Tape Physical End Matching§

Authors


  • Presented at the 63rd Annual Meeting of the American Academy of Forensic Sciences, February 25, 2011, in Chicago, IL, and at the California Association of Criminalists Fall 2011 Seminar, May 20, 2011, in Long Beach, CA.

  • Supported by Award No. 2009-DN-BX-K235 awarded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice.

  • §

    The opinions, findings, and conclusions or recommendations expressed in this publication/program/exhibition are those of the author(s) and do not necessarily reflect those of the Department of Justice.

Additional information and reprint requests:

Kaitlin Bauer, M.S.

CA Department of Justice

Central Valley Laboratory

1306 Hughes Lane

Ripon, CA 95366

E-mail: kaitlin.bauer@doj.ca.gov

Abstract

Forensic scientists are often asked to physically compare duct tape samples found in association with criminal activity. This study was designed to statistically evaluate the error and accuracy rates associated with duct tape physical end matching. The experimental design consisted of a blind study in which three researchers independently analyzed eight types of tape subjected to four methods of separation. The lowest mean accuracy observed was 98.15%, the highest mean false-positive rate observed was 3.33%, and the highest mean false-negative rate was 2.67%. Overall, high accuracy with low false-positive and false-negative error rates were observed. This study confirms the use of physical end matching in identifying duct tape samples as matching or nonmatching and that the differences between analysts, brands, tape grades, tape color, and methods of separation have varying contributions to misidentifications and inconclusive results. This study also demonstrates the importance of peer review in duct tape analysis.

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