Lending new meaning to the phrase ‘cat burglar’, a single feline hair left at a crime scene can be traced back to an individual animal through a new method that can highlight a unique, rare genetic ‘fingerprint’.
“Hair shed by your cat lacks the hair root, so it contains very little useable DNA,” said lead author of the study, Emily Patterson, a researcher at the University of Leicester. “In practice we can only analyze mitochondrial DNA, which is passed from mothers to their offspring, and is shared among maternally related cats.”
As such, existing methods of DNA analysis makes it incredibly hard to zone-in on an individual, as much as Hollywood would have us believe otherwise. So even if forensics locate a single hair at a crime scene, it cannot provide any usable, specific information; even if it matches a cat associated with a person of interest, it will also match many other cats.
“In 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,” said study co-lead Jon Wetton, from the university’s Department of Genetics and Genome Biology. “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.”
The University of Leicester researchers have described an analysis process that amplifies the cat mitogenome in 60 overlapping amplicons (mean length 360 bp), followed by Nanopore sequencing. When treating a single cat hair that lacks nuclear DNA, this approach provided “a highly discriminating source of forensic genetic evidence.”
The method proved to be 10 times more discriminating than an earlier method looking at a shorter fragment of mitochondrial DNA.
Because of the nature of cat hair, which belongs to a coat that is shed on average three times a year, it’s very easy for this to travel on clothing and be left on site – even if someone is being incredibly careful to not leave their own DNA.
“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,” said study co-lead Mark Jobling, Professor of Genetics at the university. “The same approach could also be applied to other species – in particular, dogs.”
Cats are the second-most popular pet in the US, behind dogs, with at least one kitty reigning over some 46.5 million households, according to 2023 data research.
It’s the latest advancement in forensics that may provide more avenues of crime scene investigation. A study published in July looked at finding effective methods of extracting human DNA from dog hair, which could potentially provide important information of an event the animal may have been present at.
The research was published in the journal Forensic Science International: Genetics.
Source: University of Leicester