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                            Library & Multimedia
 Optimization of a Statistical Algorithm for Objective Comparison of Toolmarks
NCJ Number
              248845
Journal

*Journal of Forensic Sciences* Volume: 60 Issue: 2 Dated: March 2015 Pages: 303-314
Author(s)
          Ryan  Spotts;
                        L. S. Chumbley;
                        Laura  Ekstrand;
                        Song  Zhang;
                        James  Kreiser
Date Published

March 2015
Length
              12 pages
Annotation
              Due to historical legal challenges, there is a driving force for the development of objective methods of forensic toolmark identification. This study utilizes an algorithm to separate matching and nonmatching shear cut toolmarks created using 50 sequentially manufactured pliers.
Abstract
              Unlike previously analyzed striated screwdriver marks, shear cut marks contain discontinuous groups of striations, posing a more difficult test of algorithm applicability. The algorithm compares correlation between optical 3D toolmark topography data, producing a Wilcoxon rank sum test statistic. Relative magnitude of this metric separates the matching and nonmatching toolmarks. Results show a high degree of statistical separation between matching and nonmatching distributions. Further separation is achieved with optimized input parameters and implementation of a "leash" preventing a previous source of outliers; however, complete statistical separation was not achieved. This paper represents further development of objective methods of toolmark identification and further validation of the assumption that toolmarks are identifiably unique.  (Publisher abstract modified)
      
  
          Additional Details
Grant Number(s)
        2009-DNR-119


  
  
        
  Agencies
        NIJ-Sponsored


  
  
        
  Publication Type
        Research (Applied/Empirical)
                                Report (Study/Research)
                                Report (Grant Sponsored)
    
  
  
Date Published: March 1, 2015
    
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