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Monday, November 13, 2023

Before committing a crime, shave your cat

Hair Shed by Pet Cats is Useful Source of Forensic Evidence, Study Says

By Sci.News News Staff

He WILL rat you out. (photo by Will Collette)
Domestic cats are among the most common household pets.

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