DNA retention by police

What is DNA?

DNA stands for deoxyribonucleic acid, the chemical that carries the genetic code for all human life.

The study of DNA is important not only for increasing medical knowledge, but also for forensic purposes:

• because each individual’s DNA is both highly complex and unique to that person (or, at the very least, shared only by identical twins), DNA is the most powerful form of identification available,
• since DNA is found in every human cell, it is possible to gain a sample of someone’s DNA by a wide range of means: a strand of hair, a flake of skin, a mouth swab containing saliva, or a blood sample, etc. Although it is relatively easy to avoid leaving fingerprints at a crime scene, for example by wearing gloves, it is often much harder to avoid leaving DNA evidence.

Since 1985, when Sir Alec Jeffreys at the University of Leicester pioneered the development of DNA profiling, it has been possible for forensic experts to use DNA to match suspects with genetic samples taken from crime scenes. Accordingly, DNA has become an immensely powerful forensic tool in the investigation of crime.

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