In December 2001, a young woman was reported missing in Anchorage, Alaska, by her boyfriend—but she was not to be found despite all efforts. Finally, in May 2003, her mother submitted a saliva swab sample to the FBI for analysis; we determined its nuclear DNA and mtDNA profiles and entered it our Combined DNA Index System for use in the FBI’s National Missing Person DNA Database. It was there, ready for matching, when hikers discovered the severely decomposed remains of a body on Alaska’s Seward Highway that June. First, though, another agency believed the remains might match its ongoing arson case. It had a nuclear DNA profile developed from the remains—but no match! Then the Alaska crime lab and the FBI’s nuclear DNA lab got a hit between the mother’s nuclear DNA and the Alaska remains, showing a possible biological relationship. Our lab conducted mtDNA analysis on the remains, compared it to the mother’s profile, and found the match. The remains were identified by the coroner, and the case was solved.

So what on earth is mitochondrial DNA (mtDNA) analysis?

It’s complicated—a process that determines mtDNA sequences in small or degraded evidence samples, then compares them to the mtDNA of blood or saliva samples submitted from a particular investigation (victims, suspects, or relatives of missing persons) to determine whether or not they match.

When do you use it?

When your evidence samples don’t contain enough nuclear DNA (nDNA) for suitable analysis. Primarily, we conduct mtDNA analysis on hair shafts that are recovered as evidence…and on aged human remains, such as bones and teeth.

How often do we use it? As often as we can, given our resources. Last year we completed 283 cases. As of September 10 of this year, we have completed 414 cases, including cases from the National Missing Persons DNA Database.

How long does each examination take? Considerable time, as exacting care must be taken for each of our many cases: on average, about 7 months for a complete turnaround time…but we continue to shorten the time without sacrificing quality.

Who does the examinations? Currently, our Mitochondrial DNA unit is staffed with 11 forensic mtDNA examiners (including four detailed to the National Missing Persons DNA Database who analyze specimens from unidentified human remains and relatives of missing persons) and 17 mtDNA biologists. In addition, we are in the process of bringing more people and more labs online: four regional mtDNA laboratories are in the works—in Arizona, Connecticut, Minnesota, and New Jersey.

A bright future for using science in the cause of justice. As these new laboratories become operational during the next two years, the FBI will be able to nearly double its ability to deliver no-cost DNA analysis to the criminal justice community. And, incalculable, to bring resolution to the families of missing and slain loved ones.

Links: DNA Analysis 2 Unit | FBI Laboratory

Graphic: Here is an example of nucleotide sequence data generated by the 3100 Genetic Analyzer. An examiner carefully analyzes each peak from both strands of the DNA molecule. An examiner looks at over 600 of the building blocks from each sample.