Cat and dog hairs on clothes could be used to identify criminals forensically

Most pet owners end up with hair on their clothes, with cat and dog fur being particularly sticky because it is electrically charged, making it difficult to remove from fabric.

Forensic teams have known for decades that pet hair could prove vital for placing criminals at crime scenes.

But most cat hairs that are shed do not contain a root – or else the root is dead – meaning there is virtually no nuclear DNA to sequence.

Now scientists at the University of Leicester have found it is possible to identify cats using variations in their mitochondrial DNA, the battery of the cell which is passed from the mother.

Dr Jon Wetton, from Leicester University’s Department of Genetics and Genome Biology, said: “If the police have a case where there are cat hairs but no human DNA to link a suspect with a crime it is now very likely that, using our approach, we would be able to exclude the great majority of cats as the source and demonstrate a stronger link to the suspect’s cat.

“The approach could be applied to other species, dogs being the most relevant as their hairs are also frequently found on clothing.

“There will undoubtedly be several cold cases around the world where the police and forensic investigators are looking for new leads and have items of victim’s clothing bearing unidentified hairs that with this approach could finally provide that link to the offender.”Short tandem repeats

In human DNA profiling, experts look for unique repetitive areas in the genetic code called ‘‘short tandem repeats’’ which act like fingerprints.

But because most domestic cats share a handful of common ancestors, they have very similar DNA and cannot be separated from each other.

The new method screens every part of the mitochondrial DNA to detect the tiny differences.

Although mitochondrial DNA is less variable than nuclear DNA, the chance that two cats share the same type of genome in Britain is just three per cent.

Cat hair has been used in court cases before, but only when the cat had such distinctive and uncommon DNA that it could be separated from other animals.

Around 26pc of UK households own a cat and, with the average animal shedding thousands of hairs annually, the method has the potential for being extremely useful for forensics.

The new research was published in the journal Forensic Science International: Genetics.