Sir Alec Jeffreys (born in 1950 at Luton in Bedfordshire) is a British scientist.

After graduating at Oxford University, he moved to Leicester University in 1977, where he developed genetic fingerprinting, a technique to distinguish between individuals of the same species using only samples of their DNA.

His DNA technique proved useful in helping to hunt down a child molestor who had killed two girls in Leicestershire. Ultimately the suspect, Colin Pitchfork, was convicted of murder and sentenced to long prison terms after samples taken from him matched semen samples taken from the two dead girls.

He was elected an FRS in 1986 and was knighted in 1994. In 1996, he was awarded the Albert Einstein World Award of Science.