With its basis of maternally inherited genetic information, mtDNA is particularly useful when traditional nuclear DNA analysis is unlikely to yield probative information. The high copy number of mtDNA in cells enables it to be recovered in biological evidence when nuclear DNA may be sparse or degraded. It is particularly suitable for missing persons casework, because even distant relatives can be used as references when no direct reference sample is available. Complete sequencing of the mitochondrial genome (mtGenome), which includes coding regions of the molecule, has been shown to be superior in distinguishing unrelated individuals. Although mtGenome sequence data have long been available in resources such as GenBank, they do not properly represent randomly sampled populations and do not meet the stringent data quality standards required for forensic use. In order to address this gap in population data, NIJ funded a project that developed a forensic-quality mtGenome population database with more than 500 complete mtGenomes that span three U.S. population groups. This database provides a foundation of forensically robust reference population data, with complete and accurate information that will ultimately improve discrimination between forensic samples with distinct maternal lineages. This complete mtGenome reference database will enable enhanced identification capabilities for laboratories that currently use mtDNA for identifying missing persons. This database will be continually improved by adding more forensic-quality mtGenome data developed by collaborating laboratories worldwide.