Interpreting DNA Mixtures

    Volume 42, Issue 2 (March 1997)

    ISSN: 0022-1198

    CODEN: JFSOAD

    Page Count: 10


    Weir, BS
    North Carolina State University, Raleigh, NC

    Triggs, CM
    University of Auckland, Auckland,

    Buckleton, J
    ESR: Forensic, Mt. Albert Science Center, Auckland, New Zealand

    Walsh, KAJ
    ESR: Forensic, Mt. Albert Science Center, Auckland, New Zealand

    Stowell, LI
    ESR: Forensic, Mt. Albert Science Center, Auckland, New Zealand

    Starling, L
    ESR: Forensic, Mt. Albert Science Center, Auckland, New Zealand

    (Received 2 January 1996; accepted 5 August 1996)

    Abstract

    The interpretation of mixed DNA stains is explained in the context of likelihood ratios. The probabilities for the mixed-stain profile are evaluated under alternative explanations that specify the numbers of contributors and the profiles of any known contributors. Interpretations based simply on the frequencies with which random members of a population would not be excluded from a mixed-stain profile do not make use of all the information, and may overstate the strength of the evidence against included people. The effects of the numbers of contributors depends on whether all the alleles at a locus are present in the mixed stain. A general equation is given to allow likelihood ratios to be calculated, and includes the “2p” modification suggested by the 1996 NRC report. This modification is not always conservative. A computer program to perform calculations is available.


    Paper ID: JFS14100J

    DOI: 10.1520/JFS14100J

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    Author
    Title Interpreting DNA Mixtures
    Symposium , 0000-00-00
    Committee E30