Eight out of 10 Crime Scene Investigators prefer cat litter!

Published: 26 September 2011 at 15:20

Anglia Ruskin scientists research best materials to detect presence of petrol

Forensic scientists at Anglia Ruskin University have revealed a novel tool that could be used to help catch arsonists – cat litter.

The research, carried out by Dr Sarah Hall, Dr Lata Gautam, Vicky Bacchus and Garry White, has shown that cat litter is the best material to detect traces of petrol on hard surfaces such as concrete, and this could prove invaluable to Crime Scene Investigators (CSIs) across the country.

Most brands of cat litter contain the mineral sodium bentonite, which is a clay formed from volcanic ash. Up close, the clay is full of microscopic tunnels with a network of capillaries which retains the petrol on the surface without reacting.

Petrol is a complex mixture of around 200 components and 15 of these are targeted during its analysis to give a positive identification. This is a requirement for the presence of petrol to be proven in court.

Garry White, who is studying for a PhD at Anglia Ruskin, explained:

“When investigating a fire, a CSI might detect that petrol is present either by smelling it themselves or by using specially-trained sniffer dogs.

“However, because the CSIs usually arrive much later after the incident, some of the petrol would have evaporated or soaked into the floor, sometimes leaving just a stain. The CSI will need to obtain a sample and if the floor is concrete this poses a major problem.

“There are two ways of testing for the presence of petrol on hard floors; you can either dig up part of the floor to analyse in the lab or you can use a substance to try and soak up the petrol from the floor.

“As well as it being difficult to transport, the problem with digging up concrete is that no matter how carefully you do it, there is always the risk of contamination. Small pieces of concrete and dust, which might contain traces of petrol or other contaminants, could be carried in the air and deposited elsewhere in the crime scene.

“There are currently no reliable, or standard, products used by CSIs to sample petrol for later detection. However, our research has shown that cat litter is the best product available and, most importantly, fulfils the criteria laid down by UK courts.

“We surveyed CSIs across the country and discovered that they used a range of products, ranging from sand and window squeegees to more bizarre materials such as flour, mashed potato and sanitary towels. However, nobody in the UK was using cat litter which, as any cat owner will know, is cheap and easily available.”

The next stage of the research will see the scientists attempt to adapt the cat litter to improve its ability to detect other flammable materials, particularly diesel. The aim is to develop a universal adsorbent to aid detection of a range of ignitable liquids and to contribute to a standard method that is used in fire investigation, and accepted by courts, across the world.