The framework for a crime laboratory to develop mitochondrial DNA (mtDNA) interpretation guidelines begins with quality assurance or quality control. An essential practice for mtDNA typing is to minimize and monitor contamination within the laboratory. Using appropriate quality control measures can attain reliable results. Quality assurance or quality control is followed by data interpretation. The crime laboratory must establish criteria to assign nucleotide base calls to appropriate peaks or bands and to determine whether the results are of sufficient quality for interpretation purposes. The overall quality of the electropherogram data must be assessed and the results examined. Reporting results continues this framework in the development of mtDNA interpretation guidelines. The laboratory must define conditions under which the data would lead to the conclusion that an individual can or cannot be eliminated as a possible source of the mtDNA. Lastly, the weight of evidence concludes the framework. The mtDNA profile of a reference sample and an evidence sample that cannot be excluded as potentially originating from the same source can be searched in a population database. The interpretation of mtDNA nucleotide sequencing results in casework is a matter of professional judgment and expertise. Even though there are general guidelines, it is important that each laboratory develop and implement written guidelines for the interpretation of analytical results. References