DNA identification

DNA identification is, in US law, the forensic process in which a DNA profile obtained from unknown biological material — for example from an unidentified body — is compared with known reference samples in order to establish a person's identity. The method is not limited to criminal investigation; it is also used systematically to identify unknown deceased persons and missing persons where no other form of identification has been possible.

The basis for national coordination of DNA identification in the United States is the Federal DNA Identification Act of 1994, which authorised the FBI to establish and administer a national DNA index for law enforcement purposes. This index, known as CODIS — the Combined DNA Index System — makes it possible to compare DNA profiles across state lines and between federal authorities. CODIS distinguishes between profiles from known individuals and profiles from unknown biological material. When DNA from an unidentified body is analysed, the profile is uploaded to the system and automatically compared with existing profiles. A match may arise if the deceased was previously registered in the system, or if a relative has provided a reference sample in connection with a missing person report.

The case of the hiker known as 'Mostly Harmless' illustrates precisely this practice: the deceased man remained unidentified for several years until DNA analysis and comparison with genetic material from family members finally made it possible to establish his identity. The process was not a criminal investigation in the traditional sense, but an identification case driven by forensic and humanitarian considerations.

DNA identification differs from broader genetic research in its narrow law enforcement purpose: the aim is unambiguously to link biological material to a specific person, not to map genetic characteristics in general.