Cat hair can be used to link criminals to crime scenes

Researchers at the University of Leicester have discovered a novel way of connecting criminals to crime scenes: cat hair. The new study reveals that the DNA found in a single strand of cat hair could be sufficient to create a link between a suspect and a crime scene, or even a victim.

Forensic investigations 

With 26 percent of households in the UK owning a cat, and considering the vast amount of hair these pets shed annually, it’s almost certain that traces of a cat’s presence will be found on individuals who have been in the vicinity of these furry creatures. This has significant implications for forensic investigations, providing a new avenue for collecting evidence in criminal cases.

Even if a human perpetrator is careful enough to avoid leaving behind their own DNA, the cat hair transferred from the scene of the crime can act as a genetic marker. The hair itself contains unique DNA that could be the key to associating a suspect with a particular location or person involved in a criminal incident.

Wealth of DNA information 

In the recently published paper in Forensic Science International: Genetics, the experts outlined a refined method capable of extracting a wealth of DNA information from a single piece of cat hair.

“Hair shed by your cat lacks the hair root, so it contains very little usable DNA. In practice we can only analyze mitochondrial DNA, which is passed from mothers to their offspring, and is shared among maternally related cats,” said lead author Emily Patterson, a PhD student at Leicester.

This limitation means that while the hair DNA can’t be used to identify a specific cat, it is crucial to extract as much information as possible when conducting forensic tests. 

Innovative method

The team’s innovative method allows for the analysis of the entire mitochondrial DNA sequence, providing results that are approximately ten times more discriminating than previous techniques, which only examined a small fragment of the DNA.

Dr. Jon Wetton from the University’s Department of Genetics & Genome Biology, who co-led the study, shared insights from a previous murder case. 

“We applied the earlier technique but were fortunate that the suspect’s cat had an uncommon mitochondrial variant, as most cat lineages couldn’t be distinguished from each other. But with our new approach virtually every cat has a rare DNA type and so the test will almost certainly be informative if hairs are found.”

Valuable source of evidence

The method was put to the test in a real-world scenario involving a lost cat, successfully matching the DNA from the cat’s skeletal remains to that of hair from a surviving male offspring.

Professor Mark Jobling, a Genetics expert and study co-lead, highlighted the broader implications of their findings: “In criminal cases where there is no human DNA available to test, pet hair is a valuable source of linking evidence, and our method makes it much more powerful. The same approach could also be applied to other species – in particular, dogs.”

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