Leicester forensic experts create UK’s first cat DNA database

by jeeg 19. August 2013 21:50

University of Leicester forensic scientists have created the UK’s first cat DNA database – which has already helped convict a killer.

Experts in the University’s Department of Genetics have compiled a database of DNA from 152 cats around the country.

The database was used to demonstrate the likelihood that cat hairs found on the dismembered torso of Hampshire man David Guy belonged to “Tinker”, a cat owned by main suspect David Hilder.

This evidence was used as part of the prosecution case leading to the successful conviction of Hilder for manslaughter.

Dr Jon Wetton, who led the project, said: “This is the first time cat DNA has been used in a criminal trial in the UK. We now hope to publish the database so it can be used in future crime investigations.

“This could be a real boon for forensic science, as the 10 million cats in the UK are unwittingly tagging the clothes and furnishings in more than a quarter of households.”

In July 2012, the torso of David Guy was found on a Southsea beach wrapped in a curtain on which eight cat hairs were found.

Hampshire Constabulary sent the hairs to California for analysis, where the scientists examined the cat’s mitochondrial DNA – a type of DNA contained in small structures within cells, and passed down the maternal line.

The mitochondrial results showed not only a match with the suspect’s cat, “Tinker”, but also that the same DNA type had not been seen among 493 randomly sampled US cats.

The police were keen to know if the type was equally rare in the UK – and, more specifically, in the area of the crime.

Hampshire police tracked down Dr Jon Wetton – who had created a similar database of UK dogs while working with the Forensic Science Service (FSS).

Dr Wetton said: “I was approached by Hampshire police, who wanted to know the evidential strength of the match. I explained that could only be determined with reference to a database of UK cats - which did not exist at the time.

“Having produced a similar database for UK dogs during my previous employment with the Forensic Science Service, we proposed creating a UK cat database from scratch.”

With PhD student Barbara Ottolini carrying out the lab work, 152 cats from England were tested, within an impressively short timescale.

The team were able to get the samples from a company, which handles analysis of blood samples from pets for vets across the country.

The samples showed cats’ ages, gender and postcode – with 23 cats from Southsea and another 129 from a range of places throughout the rest of the country.

Only three of the samples obtained matched the hairs from the crime scene, confirming that it was indeed an uncommon type in the UK.

This evidence was presented at Winchester Crown Court, and formed part of the prosecution case successfully convicting David Hilder for manslaughter.

Dr Wetton said: “Within each cat hair are two types of DNA, individual-specific ‘nuclear DNA’ detectable in the roots of some larger hairs, and ‘mitochondrial DNA’ which is shared by all maternally-related individuals and can be found even in the finest hair shafts.

“Animal DNA offers a way of linking people to places and items through the transfer of their pet’s hairs.”

PhD student Barbara Ottolini said: “The police were lucky in this case, as most mitochondrial types are common when tested with the technique we used here.

“We would like to use cutting-edge DNA sequencing methods to identify further variation in cat mitochondrial DNA to maximise the discriminating power of the evidence”.

As well as continuing to use the database for analysis of mitochondrial DNA, the team also hopes to use their collection of cat DNAs to evaluate much more discriminating nuclear DNA tests.

Prof Mark Jobling, who leads the lab where the work was done, said: “Having created a similar database of UK dogs while working with the Forensic Science Service (FSS), Jon Wetton was the ideal person to lead the creation of a similar database of UK cats”.

The work was paid for by Hampshire Constabulary, and indirectly by the Leverhulme Trust, which provides the support for Dr Wetton’s post.

Dr Wetton said: “The FSS closure has massively reduced forensic research capacity within the UK. It will increasingly be Universities that will have to take up the slack, but funds are needed.

“One of the missions of the University of Leicester’s Alec Jeffreys Forensic Science Institute is to source such funds, so that larger-scale research projects can be undertaken in the future at the home of DNA fingerprinting.”

University of Leceister Press Office


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