Uncertainty in the Number of Contributors in 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)