ISSUE 53 Expert Witness Journal - Journal - Page 38
Study Shows Forensic
Evidence Can Survive
Underwater for Weeks
Forensic fibres can survive underwater for much longer than previously thought – which could
help criminal investigators uncover vital evidence
New research led by Staffordshire University’s
Centre for Crime, Justice and Security has found that
fibre evidence can survive on fabrics underwater for
several weeks.
PhD researcher Afsané Kruszelnicki said: “It would
be expected that a higher flow rate would have a lower
number of retained fibres compared to a lower flow
rate, yet no significant difference was seen in all but
one condition.
Claire Gwinnett, Professor of Forensic and Environmental Science, explained: “Evidence, such as
weapons and victim’s bodies, are often found in
aquatic environments including rivers and lakes.
“Even after four weeks, the lowest percentage of
remaining fibres was 33.4%. This clearly indicates that
it is extremely valuable to search for fibre evidence
even after a long exposure time.”
“However, if items have been submerged in water for
more than seven days then many forensic examiners
believe that any valuable trace evidence will be gone
and won’t seek it out.”
Professor Gwinnett said: “Our findings could change
how police direct investigations and help to uncover
forensic evidence that was previously thought to
be lost. We hope this will help investigators to
identify more suspects and ultimately lead to more
convictions.
To date, very few studies have investigated fibre
persistence on fabrics submerged underwater. The
dynamic nature of aquatic environments mean that
the studies are difficult to conduct in situ and variables,
such as water flow rate, are not possible to control.
“The study also highlights the benefits of using
mesocosms which mimic realistic aquatic environments in a controlled setting. This is the first time that
mesocosms have been used to look at forensic evidence and we hope it will pave the way for further
studies to investigate different types of trace evidence
such as gunshot residue, pollen, fingerprints or
DNA.”
The Forensic Fibre Freshwater (3F) project, funded
by the European Commission’s Transnational Access
Programme, was conducted in partnership with Lunz
Mesocosm Infrastructure (LMI), WasserCluster Lunz,
the University of Vienna and Italy’s University of
Milano-Bicocca.
Dr Katrin Attermeyer, coordinator of the stream
mesocosms in Lunz am See and aquatic microbial
ecologist at WasserCluster Lunz and the University of
Vienna, added: “This interdisciplinary collaboration
between forensic scientists and aquatic ecologists has
not only provided insights into other sciences, but has
also shown that mesocosms, traditionally used to answer ecological questions, are a valuable asset to other
research areas such as forensic sciences.”
This study used artificial streams, known as
mesocosms, to investigate the persistence rate of
polyester fibres on different fabric types over a
four-week exposure time.
Usually used for ecological research, this is the first
time that mesocosms have been employed to look at
forensic evidence.
Two flow velocities, high and low, were used on three
textiles: woolen/nylon mix carpet, 100% polyester
fleece, and 95% polyester/5% elastane sports vest.
Read the full paper An Investigation into the Use of
Riverine Mesocosms to Analyse the Effect of Flow Velocity and Recipient Textiles on Forensic Fibre Persistence Studies published in Forensic Science
International.
https://www.sciencedirect.com/science/article/pii/S037907382
3002682?utm_campaign=STMJ_AUTH_SERV_PUBLISHED&utm_medium=email&utm_acid=99572987&
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Initial loss rates were highest for the first hour of
submergence for the carpet, fleece and sports vest.
However, persistence rates remained mostly constant
after 24 hours for all textiles and the two flow rates
used did not significantly affect fibre persistence.
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