The Department of Forensic Biology, New York City Office of Chief Medical Examiner, is responsible for all of the City's DNA testing in all criminal cases, such as homicides, sexual assaults, and property crimes. DNA testing is also conducted for body identification and missing persons cases. The DNA testing methodologies used include short tandem repeat (STR) analysis of human nuclear genomic DNA and DNA sequencing of mitochondrial DNA (mtDNA). Generally, mtDNA analysis is many orders of magnitude less discriminative than is STR nuclear DNA testing. Yet occasions and sample types do arise where nuclear DNA testing is inconclusive while mtDNA testing provides a conclusive result. Therefore mtDNA testing is used as supporting evidence for STR nuclear results and in cases where STR nuclear DNA testing fails to give results. This talk will review the current methodologies for mtDNA testing at the NYC Office of Chief Medical Examiner in addition to presenting several case examples where mtDNA testing provided useful results.