FORENSIC SCIENCES Interpretation of Complex Forensic DNA Mixtures

Forensic evidentiary samples routinely contain DNA from multiple contributors. The interpretation of these mixtures can be a challenging task for the DNA scientist. Several approaches are discussed (no calculation- qualitative state-ment; probability of exclusion; likelihood ratio estimates; presumptive genotype assignment based on peak heights), which have been employed to assess the significance of an inclusion/match when DNA mixtures have been detected in casework samples. These statistical approaches are discussed in light of technical challenges that can arise when evaluating evidentiary samples. Key words: criminology; forensic medicine; laboratories; polymerase chain reaction; polymorphism; polymorphism, restric-tion fragment length; United States The detection and interpretation of mixtures is a routine, yet often challenging aspect of forensic DNA analysis. This process can be complicated by a num-ber of factors, including possible allele overlap among an unknown number of contributors, 3-allele patterns, stochastic fluctuation with low quantity or degraded template, the semi-quantitative activity o