"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, powdered 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."