MessageToEagle.com - Foods have often been overlooked as items of evidence because they have
notoriously difficult surfaces to recover prints from.
Now, forensic scientists at the University of Abertay Dundee are able to help recover latent
fingerprints from different types of food, by modifying an existing technique that was initially designed
to recover fingerprints from the sticky side of adhesive tape.
Up to the present time, only two other studies (one in India and the other in Slovenia) have ever reported
successfully recovering fingerprints from foods, but the research was based chemical substances that are
not routinely used in Britain.
Forensic fingerprint experts help law enforcement officials solve crimes.
“Although there are proven techniques to recover fingerprints from many different surfaces these days, there
are some surfaces that remain elusive, such as feathers, human skin, and animal skin," Dennis Gentles, a former
crime scene examiner and forensic scientist who has worked at Abertay University for
the past ten years, explained.
“Foods such as fruits and vegetables used to be in that category, because their surfaces vary so much – not
just in their colour and texture, but in their porosity as well. These factors made recovering fingerprints
problematic because some techniques, for example, work on porous surfaces while others only work on non-porous
“Using the right technique is of the utmost importance because if you use the wrong one, it can damage the
print and destroy what could have been a vital piece of evidence.
“The fact that we’ve managed to successfully recover prints from such difficult surfaces as foods is another
step forward in the fight against crime.
It may not seem like much, but a piece of fruit might just be the only
surface that has been handled in a crime scene so developing a trusted and tested technique to recover fingerprints
from such surfaces is something to be valued by crime scene examiners.”
Because of the differences between the substances available in the UK and those used in the other studies,
the team at Abertay began by testing a selection of the techniques currently recommended by the Home Office
for recovering fingerprints.
Disappointingly, their results showed that few of these techniques – when applied to foods including apples,
tomatoes, onions and potatoes – produced a print of high enough quality for it to be presented as evidence in court.
However, when they modified a substance known as Powder Suspension (PS) – a thick, tar-like substance – they
found it produced a clear, high-quality mark on the smooth-surfaced food items such as the onions, apples and tomatoes.
“There are about 15 techniques that are currently recommended by the Home Office for recovering prints – from
a variety of surfaces – and research teams are constantly refining them and developing new ones so that
the police can get as much evidence of as high a quality as possible to help with an investigation," Dennis Gentles said.
“Although Powder Suspension was initially developed to recover prints from the sticky side of adhesive tape,
it’s since been found to work on other surfaces, so we wondered whether it would work on foods, as this was
something it hadn’t been tested on before.
“The smooth surface of an apple is very different from that of sticky tape though, so such a thick substance
wasn’t going to produce the same results on such a different surface. So we tried altering the formulation a
bit, making it more dilute than that suggested by the Home Office, and found that it out-performed all
the other methods we tested.
“Although there’s still a considerable amount of research to do before we can recommend techniques for all
types of foods, we’ve shown for the first time that it really is possible to recover fingerprints from
them – something that was previously thought to be unachievable.
This means the police will now be able to gather even more evidence to present in court, adding more
weight to their investigations.”
The research is published in the forensic science journal “Science & Justice”.
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