DNA Casework

DNA Strand on Black Background

The Mission 

The DNA Casework Unit (DCU) provides forensic DNA examinations to the FBI and other duly constituted law enforcement agencies in support of criminal, missing persons, and intelligence cases through evidence testing using forensic serological, mitochondrial DNA, and nuclear DNA methodologies.

The Team 

Unit chief, forensic examiners, biologists, DNA technical specialists, DNA program specialists, management and program analysts, and contract employees.

The Work 

Deoxyribonucleic acid (DNA) analysis can occur in body fluid stains and other biological tissues recovered from items of evidence. The DNA testing results obtained from evidence samples are compared to DNA from reference samples collected from known individuals. Such analyses may be able to associate victims and suspects with each other, with evidence items, or with a crime scene. The FBI can conduct nuclear, Y-chromosome, and/or mitochondrial DNA testing on evidence samples as appropriate.


The DCU performs serological testing to detect and characterize body fluids such as blood and semen on items of evidence.

Nuclear DNA

Nuclear DNA (nDNA) is the most discriminating and is typically analyzed in evidence containing body fluids, skin cells, bones, and hairs that have tissue at their root ends. The power of nDNA testing lies in the ability to identify an individual as being the source of the DNA obtained from an evidence item, or by excluding an individual as a contributor to the DNA evidence.

Y-chromosome DNA testing is a form of nuclear DNA testing that is specific to the male chromosome, also known as the Y-chromosome. This type of testing can be useful for sexual assaults, missing persons, and intelligence cases. The Y-chromosome is transmitted from father to son as a complete set; therefore, anyone in the paternal lineage will have the same Y-chromosome profile. Due to multiple relatives having the same Y-chromosome profile, unique identifications are not possible from Y-chromosome analysis.

Mitochondrial DNA

Mitochondrial DNA (mtDNA) is a form of DNA that is transmitted from mother to child in a complete set; therefore, anyone in the maternal lineage will have the same mtDNA profile. This type of DNA testing can be useful on evidence items such as naturally shed hairs, hair fragments, bones, and teeth. MtDNA analysis is highly sensitive and may allow scientists to obtain information from items of evidence associated with cold cases, missing persons, samples from mass disasters, and small pieces of evidence containing little biological material. However, since multiple individuals can have the same mtDNA profile, unique identifications are not possible from mtDNA analysis.


The DCU offers kinship analysis, which is the comparison performed to determine the possible familial relatedness between an evidence item and a known item using a software program. The DCU also offers criminal paternity testing as part of criminal, intelligence, and missing person casework. When appropriate, DNA results from evidence relating to criminal cases and missing persons will be uploaded into the National DNA Index System (NDIS).

Unit Operations 

Under the direction of the DCU chief, unit operations effectively cascade across supervisors, examiners, and biologists. An examiner obtains a case and makes decisions based on the items of evidence available to test. The examiner then directs the biologist to perform the appropriate examinations on the specific items of evidence; once completed, the biologist provides their documentation notes to the examiner. The examiner then interprets the data, writes a report, and testifies as necessary in court.

The DNA Support Unit (DSU) ensures the DCU remains flexible and responsive to unpredictable case volume and evolving intelligence threats. The DSU is responsible for oversight and management of the FBI Laboratory's DNA programs and initiatives in research, validation, quality assurance, training, and information technology. The DSU enhances and maintains the Laboratory Division's capacity to conduct high-quality DNA and serological examinations in a skilled, progressive, and responsive manner to ensure compliance with all applicable guidelines and standards.

NIJ-FBI Sexual Assault Kit Partnership 

The National Institute of Justice (NIJ) and the FBI Laboratory have formed a partnership to help address one of the most difficult and complex issues facing our nation’s criminal justice system: unsubmitted sexual assault kits (SAKs). The FBI will be a centralized testing laboratory for SAKs, commonly known as rape kits, to be submitted from the nation’s law enforcement agencies and public forensic laboratories.

Each month, the DCU will process and test a limited number of previously unsubmitted SAKs while scientists at NIJ collect and analyze data about the kits. The goal of this project is to better understand the issues concerning the handling of SAKs and suggest ways to improve the collection and processing of quality DNA evidence. Additionally, NIJ will gather information from the program to help inform training practices and testing protocols for SAKs and improve the quality and practices for collecting evidence and processing sexual assault kits.

Contact Us 

If you have any questions about serological and/or DNA testing, please contact the DCU at (703) 632-8446, or write to the unit at:

FBI Laboratory
DNA Casework Unit
2501 Investigation Parkway
Quantico, VA 22135