DNA fingerprinting DNA or deoxyribo nucleic acid is the genetic material in all humans. In DNA fingerprint a unique array of DNA fragments is examined by using many tandem-repeat sites, as each person carries a unique combination of repeat numbers. The tandem-repeat sites can be detected by 'restriction fragment length polymorphism or RFLPs' where DNA fragments of different sizes are cleaved by restriction enzymes. Thus DNA fingerprinting can be used to identify criminals from the DNA in blood or small amounts of tissue left at a crime scene.