By Dr Lisa Smith, senior lecturer in criminology, University of Leicester and Professor Mark Jobling, professor of genetics, University of Leicester.
Listen to Sir Alec Jeffreys being interviewed by Professor Alison Woollard FRSB at the RSB’s fundraising event in May 2016.
Today, thanks partly to TV’s CSI franchise, everyone is familiar with the DNA profile – super-sensitive, and individually unique. But go back 40 years, and DNA-based forensic analysis did not exist. Instead, there was an industry that analysed not DNA itself, but its products – proteins. It started in 1900 with the discovery, by Karl Landsteiner, of the ABO blood group. He realised that this system could exclude a suspect from depositing a blood-stain at a crime-scene. Given the small number of different types, the average power of exclusion was low, but this increased once enzyme variants in blood were included. Because each variant is inherited independently, the frequencies of types (alleles) for each system could be multiplied, increasing discrimination. Read more