DNA fingerprinting is a laboratory technique used to establish a link between biological evidence and a suspect in a criminal investigation. A DNA sample taken from a crime scene is compared to a DNA sample from a suspect. If the two DNA profiles are a match, then the evidence came from that suspect. Conversely, if the two DNA profiles do not match, then the evidence may not have come from the suspect. Fingerprints of DNA are also used to establish paternity.
The DNA profile (also called DNA fingerprint, DNA test or DNA typing) is a forensic technique used to identify individuals by characteristics of their DNA. A DNA profile is a small set of DNA variations that is very likely to be different in all unrelated individuals, making it as unique to individuals as fingerprints (hence the alternative name for the technique). The DNA profile should not be confused with complete genome sequencing. First used in 1984, DNA analysis is used, for example, in kinship and criminal investigation, to identify a person or place a person at a crime scene, techniques that are currently used worldwide in Forensic science to facilitate the work of police detectives and help clarify paternity and immigration disputes. DNA fingerprints have also been widely used in the study of animal and floral populations and have revolutionized the fields of zoology, botany and agriculture.
Although 99.9% of the human DNA sequences are the same in each person, enough of the DNA is different that it is possible to distinguish one individual from another, unless they are monozygotic ("identical") twins. The DNA profile uses repetitive ("repeated") sequences that are highly variable, called variable number tandem repeats (VNTRs), in particular short tandem repeats (STRs), also known as microsatellites and minisatellites. VNTR loci are very similar among closely related individuals but are so variable that unrelated individuals are very unlikely to have the same VNTRs. The modern DNA profiling process was developed in 1984 by Sir Alec Jeffreys while working at the Department of Genetics at the University of Leicester.