MODEL RELEASED. DNA autoradiograms. Female technician examining DNA (deoxyribonucleic acid) autoradiograms or genetic fingerprints. A sample of DNA can be taken from body tissue such as hair, blood and saliva. The sample is then cut into segments with enzymes and a process known as electrophoresis orders the segments by size. The segments are then exposed on X-ray film where they form bands of black bars. Each band represents the position of one of the four DNA bases, which forms the genetic code. The banding is unique to each individual and it is this that is known as the fingerprint". It can be used to prove people are related and can help identify criminals."