Traditional genetic fingerprinting had relied on bodily fluids and hair, but by 1999 the team that Gill was part of was using PCR to develop a much more sensitive method, known as ‘low copy number (LCN) DNA profiling’. To get an LCN profile they needed only a few cells from a potential suspect. Whether it was a speck of dead skin, the sweat from a fingerprint or the dried saliva from a postage stamp, the required amount of bodily substance had spiralled down from the size of a ten pence piece to one millionth of a grain of salt.
