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Uncertainty in the Number of Contributors in the Proposed New CODIS Set

NCJ Number
Date Published
November 2015
5 pages
This study examined the probability of a mixed DNA profile appearing as having originated from a fewer number of contributors for the African American, Asian, Caucasian and Hispanic US populations, using a range of locus configurations from the proposed new CODIS set.
The probability that multiple contributors are detected within a forensic DNA profile improves as more highly polymorphic loci are analysed. The assignment of the correct number of contributors to a profile is important when interpreting the DNA profiles. These theoretical calculations were based on allele frequencies only and ignored peak heights. This analysis shows that the probability of a higher order mixture (five or six contributors) appearing as having originated from one less individual is high. This probability decreases as the number of loci tested increases. (Publisher abstract modified)

Date Published: November 1, 2015