Sir Alec John Jeffreys, CH FRS MAE[6] (born 9 January 1950)[5] is a British geneticist known for developing techniques for genetic fingerprinting and DNA profiling which are now used worldwide in forensic science to assist police detective work and to resolve paternity and immigration disputes.

[16] Jeffreys completed his Doctor of Philosophy degree on the mitochondria of cultured mammalian cells, as a postgraduate student at the Genetics Laboratory at the University of Oxford.

[8][18] Jeffreys's DNA method was first put to use in 1985 when he was asked to help in a disputed immigration case to confirm the identity of a British boy whose family was originally from Ghana.

[8] DNA fingerprinting was first used in a police forensic test to identify the killer of two teenagers, Lynda Mann and Dawn Ashworth, who had been raped and murdered in Narborough, Leicestershire, in 1983 and 1986 respectively.

Not only did Jeffreys' work, in this case, prove who the real killer was, but it exonerated Richard Buckland, initially a prime suspect, who likely would have spent his life in prison otherwise.

[22] STR profiling was further refined by a team of scientists led by Peter Gill at the Forensic Science Service in the 1990s, allowing the launch of the UK National DNA Database (NDNAD) in 1995.

Under British law, anyone arrested in England, Wales or Northern Ireland has their DNA profile taken and stored on the database whether or not they are convicted (different rules apply in Scotland).

[26] Jeffreys met his future wife, Sue Miles, in a youth club in the centre of Luton, Bedfordshire, before he became a university student,[8][15] and they married on 28 August 1971.