Hair Shed by Pet Cats is Useful Source of Forensic Evidence, Study Says
By Sci.News News Staff
Domestic cats are among the most common household pets.He WILL rat you out. (photo by Will Collette)
In the United Kingdom, for example, there are an
estimated total of about 11 million, residing in 26 % of homes.
Within such environments, cat hairs are continuously shed
and transfer readily to the belongings and clothing of associated humans.
The recovery of cat hairs from a crime scene may
therefore provide important evidence, linking a suspect and a victim, for
instance.
As shed hairs normally originate from the cat’s
undercoat, they provide minimal diagnostic characteristics and are of limited
value in microscopic comparison.
Comparative visual analysis is further complicated by
extensive variation of hairs even within a single animal.
In their new paper, Patterson and colleagues describe a
novel method that can extract maximum DNA information from just one cat hair.
“Hair shed by your cat lacks the hair root, so it contains very little usable DNA,” Patterson said.
“In practice we can only analyze mitochondrial DNA, which
is passed from mothers to their offspring, and is shared among maternally
related cats.”
“This means that hair DNA cannot individually identify a
cat, making it essential to maximize information in a forensic test.”
However, our new method enabled us to determine the
sequence of the entire mitochondrial DNA, ensuring it is around 10 times more
discriminating than a previously used technique which looked at only a short
fragment.
“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 University of Leicester’s Dr. Jon Wetton.
“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 researchers tested the method in a lost cat case,
where DNA from skeletal remains of a missing female cat could be matched with
DNA from hair from her surviving male offspring.
“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 University of Leicester’s Professor Mark
Jobling.
“The same approach could also be applied to other species
— in particular, dogs.”
The team’s paper appears in the journal Forensic Science International: Genetics.
Emily C. Patterson et al. 2023. Defining cat
mitogenome variation and accounting for numts via multiplex amplification and
Nanopore sequencing. Forensic Science International: Genetics 67:
102944; doi: 10.1016/j.fsigen.2023.102944