(1992) Blood storage. Blood samples being stored in a cryogenic freezer. The blood can be used to produce a DNA fingerprint even after years of storage. Selected DNA extracted from the blood is separated into DNA bands by electrophoresis in an agarose gel. The pattern of DNA bands is unique to each person, but related people, such as a parent & child, share some bands. DNA fingerprints can be used to prove conclusively whether people are related. It can also be used to identify and convict criminals from blood, semen or hair left at the scene of a crime. Cellmark Diagnostics, a commercial laboratory near Oxford, UK.