This web site was copied prior to January 20, 2005. It is now a Federal record managed by the National Archives and Records Administration. External links, forms, and search boxes may not function within this collection. Learn more.   [hide]



FBI Laboratory seal

FBI Laboratory heading

Graphic for DNA Analysis Unit I

The DNA Analysis Unit I analyzes body fluids and body fluid stains recovered as evidence in violent crimes. Examinations include the identification and characterization of blood, semen, saliva, and other body fluids using traditional serological techniques and related biochemical analysis. Once the stain is identified, it is characterized by DNA analysis using the restriction fragment length polymorphism (RFLP) and/or polymerase chain reaction (PCR) techniques. The results of the analyses are compared to results obtained from known blood and/or saliva samples submitted from the victims and/or suspects.  

Graphic showing a DNA examination

DNA examinations involve the analysis of biological evidence found on clothing and other substrates.
For more information about DNA evidence or the DNA Analysis Unit I, see the DNA Examinations section of the Handbook of Forensic Services.

Graphic for DNA Analysis Unit II

In 1996 the DNA Analysis Unit II began using mitochondrial DNA (mtDNA) analysis, which is applied to evidence containing small or degraded quantities of DNA from hair, bones, teeth, and body fluids. The results of mtDNA analysis are compared to blood and/or saliva submitted from the victims and/or suspects. The Unit examines evidence that may not have been suitable for significant comparison purposes prior to the development of this technique.

The Mitochondrial DNA Population Database is composed of complete nucleotide sequences of the first and second hypervariable segments of the control region of the human mitochondrial genome and consists of two main datasets. The first dataset contains individuals from populations of forensic relevance and is contributed mostly by the Scientific Working Group on DNA Analysis Methods and forensic laboratories. The second dataset, based on mtDNA concordance, contains nucleotide sequences from ethnic groups around the world.

Graphic showing mitochondrial DNA analysis

Mitochondrial DNA analysis


Both datasets are bundled in MitoSearch, a software package specifically designed for the compilation and analysis of mtDNA databases. MitoSearch estimates the relative frequency of specific sequences for the various populations represented within the database and assesses the relative relatedness of each population with reference to the size of each database.

For more information about DNA evidence or the DNA Analysis Unit II, see the DNA Examinations section of the Handbook of Forensic Services.

Back to the top

Back to the Index

Graphic link to FBI Home Page Graphic link to FBI Laboratory Graphic link to Handbook of Forensic Services
Graphic link to FBI Headquarters and Programs page Graphic link to Laboratory Services
Graphic link to Forensic Science Communications
Information revised October 2000