Professor Paul But, a biologist at the Chinese University of Hong Kong with a PhD in botany, has an unlikely nickname among his peers. 'They call me the Ghost Buster.'
But's research includes the study of indigenous plants and vegetation in the region. The bulk of his work is concerned with the authentication and quality control of traditional Chinese medicine (TCM). He has identified herbs and foods that have poisoned people and even caused death. But earned his nickname while working on a case in which he identified a poisonous herb that killed two people who had drunk it as an infusion.
'It was supposed to be clematis root which is used in TCM but there is a herb that looks very similar which is called 'poisonous Podophyllum root'. In Cantonese, we call it gwai kau which means 'ghost mortar'.'
The professor and his team developed an 'instant method' to help identify the herb, so the mistake wouldn't be repeated.
Forensic botany, like other forensic disciplines, is based on the principle that a criminal always leaves something at the crime scene, or takes something away, although in Hong Kong it has limited applications, despite the fact that a high proportion of the territory consists of green areas.
David Clarke is a former Hong Kong government chemist and has assisted in high-profile investigations such as the infamous 'jars' murders of the 1980s in which a taxi driver dismembered the bodies of a number of women and hid them in containers in his bedroom.