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                            Library & Multimedia
 A new implementation of a semi-continuous method for DNA mixture interpretation
NCJ Number
              305195
Journal

*Forensic Science International* Volume: 6 Dated: December 2022
Author(s)
          Jacob Alfieri;
                        Michael D. Coble;
                        Carole Conroy;
                        Angela Dahl;
                        Douglas R. Hares;
                        Bruce S. Weir;
                        Charles Wolock;
                        Edward Zhao;
                        Hanley Kingston;
                        Timothy W. Zolandz
Date Published

June 2022
Length
              11 pages
Annotation
              A new calculation module within the PopStats module of the CODIS software package, based on the underlying mathematics presented in the MixKin software package, has been developed for assigning the Likelihood Ratio (LR) of DNA mixture profiles.
Abstract
              This module uses a semi-continuous model that allows for population structure and allelic drop-out and drop-in but does not require allelic peak heights or other laboratory-specific parameters. This new implementation (named SC Mixture), like MixKin, does not specify or estimate a probability of drop-out. Instead, each contributor to a mixture has an independent drop-out rate, and the probability of the mixture profile for a specified proposition concerning the contributors is integrated over the range of possible drop-out rates. The allelic drop-in rate and the population structure parameter, theta, used by the software are specified by the user. The user can examine up to five contributors to a mixture, however, conditioning on assumed contributors and limiting the number of unknowns in both numerator and denominator hypotheses greatly improves performance. We report results from an extensive validation study performed for ten mixtures with each of one (single source), two, three, four, or five contributors, with four combinations of drop-in rate and a population structure parameter. Each mixture was run as a complete profile or with the random removal of alleles to simulate drop-out. All 1620 combinations were evaluated with PopStats, MixKin, and LRmix and considerable consistency was found among the results with all three packages. (Publisher abstract provided)
      
  
          Additional Details
Grant Number(s)
        2020-DQ-BX-0022


  
  
        
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        NIJ-Sponsored


  
  
        
  Publication Type
        Research (Applied/Empirical)


  
  
        
  Award
        Population Genetic Issues for Forensic DNA Profiles
    
  
  
Date Published: June 1, 2022
    
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