We have all watched TV forensic pathologists pause whilst photographing the body, grab a pair of tweezers and bag a piece of trace evidence from under the victim’s fingernails or inside a wound. In the storyline, this fibre or sliver of glass proves to be crucial damning evidence against the killer. So how important is trace evidence and is it true every contact leaves a trace?

Avid readers of crime fiction will be familiar with the ‘little grey cells’ of Hercule Poirot and Sherlock Holmes’ examination of trace evidence. Less well known is Song Ci, whose casebook ‘Washing Away of Wrongs’ provided coroners with a step-by-step guide to autopsy and forensic investigation. Why is his work so significant?