One step ahead

A team of Spanish and British scientists has developed a laser-ablation technique to detect variations in the sulphur isotopes of a single hair over time.

The information shows up changes in a person's eating habits and their movements between different countries, which could help police to undermine the alibis of international terrorists.

A group of researchers from the LGC Chemical Metrology Laboratory in the UK and the University of Oviedo in Spain, came up with the method to detect how the proportions of isotopes in a chemical element vary throughout the length of a single hair.

Their objective is to be able to use the method to track the geographical movements of people, including international crime suspects and victims.

The scientists focused on the most abundant sulphur isotopes in hair keratin - sulphur-32 (32S), which accounts for about 95 per cent, and sulphur-34 (34S), which makes up around four per cent. This proportion can change slightly in response to people's diets and if they travel from one country to another, and the technique is able to detect these small variations.