Dutch Police Are DNA Testing 21,500 Men to Solve A 20-Year-Old Murder

In 1986, a technique called “DNA fingerprinting” was used for the first time in a criminal investigation, when a geneticist named Alec Jeffreys realised that when DNA was extracted from cells and attached to photographic film, it developed as a sequence of bars that could uniquely identify someone. His accidental discovery helped nail the suspect in the murder of 15-year-old Dawn Ashworth. Since then, for better and for worse, DNA has become gold-standard evidence that has led to thousands of convictions.