Forensic Profiling

The FBI Laboratory began analyzing mitochondrial DNA in casework in 1996. Since that time, the DNA Analysis Unit II uses mtDNA sequencing techniques and has processed approximately 500 cases and recently created the National Missing Persons DNA Database to help the law enforcement community with missing person cases. Mitochondrial DNA analysis, while similar to the forensic nuclear DNA analysis found in the news so often in the past few years, has several differences that impact its analysis. Because current cases, as well as many cold cases housed in the archives of law enforcement agencies, potentially could benefit from mtDNA analysis, it becomes important for investigators to understand the capability of this technique as a crime-solving tool.

 

Scientists can create a DNA profile of an individual using samples from blood, bone, hair, and other body tissues and products. In criminal cases, this generally involves obtaining samples from crime-scene evidence. If DNA is found and thought to be that of a suspect or a person in question, they can extract the DNA of the person and compare it to the DNA found at the crime scene. If the DNA markers match, there is a very high probability that the suspect contributed the sample found.

 

DNA from crime scenes also can be compared to profiles stored in a database. If biological evidence from crime scenes is collected and stored properly, valuable DNA can be found on evidence that may be decades old. Therefore, old cases that were previously thought unsolvable may contain valuable DNA evidence capable of identifying the man or woman who committed the crime. DNA evidence collected from a crime scene can implicate or eliminate a suspect, similar to the use of fingerprints. It also can analyze unidentified remains through comparisons with DNA from relatives. Additionally, when evidence from one crime scene is compared with evidence from another using CODIS, those crime scenes can be linked to the same perpetrator locally, statewide, and even nationally.

Maternal Lineage Tests

In this day and age, people can have tests that trace one’s maternal lineage. A person can submit his/her mtDNA and get results of his/her maternal ancestry and trace back to a certain person of the female line. Although expensive, many people use these tests to establish their family trees, or to find long-lost family members. Unlike an Ancestry DNA test, which traces geographical roots back thousands of years, a maternal lineage test gives scientific confirmation of more recent relationships, identifying possible relatives from a person’s genealogic research.