Matthew T. Mangino
GateHouse Media
March 6, 2020
The FBI has apprehended and convicted suspects in criminal
cases by analyzing light and dark patches - wear marks - along the seams of the
suspects’ blue jeans.
and convicted suspects in criminal cases by analyzing light
and dark patches - wear marks - along the seams of the suspects’ blue jeans.
A leading proponent of blue jean analysis is Richard W.
Vorder Bruegge of the FBI’s Forensic Audio, Video and Image Analysis Unit in
Quantico, Virginia.
According to ProPublica, an independent group of
investigative journalists, Vorder Bruegge wrote an article in the 1999 Journal
of Forensic Sciences on the photographic analysis of denim “trousers” arguing
that wear marks create, effectively, a barcode that is unique on every pair.
“Every piece of clothing that you own is going to undergo abuse
during your lifetime,” Vorder Bruegge said. “If you’re a kid, maybe you’re
sliding down hills and getting a lot of scrapes on the jeans. Or maybe your
jeans get washed and ironed. But you’re rubbing them back and forth, and the
blue dye is abraded.”
Apparently, Vorder Bruegge believes that those markings can
be identified to the exclusion of nearly every other pair of jeans on earth.
Last year, ProPublica conducted an investigation that
revealed FBI examiners have tied defendants to crimes in thousands of cases by
using crime scene photographs in unproven ways and, at times, have given jurors
baseless statistics to say the risk of error in their analyses was extremely
low.
As a result, Hany Farid, a University of California,
Berkeley, computer science professor and leading forensic image analyst, and
Sophie Nightingale, a postdoctoral researcher in image science, tested the
FBI’s method and found several serious flaws.
In 1998, the FBI’s Vorder Bruegge explained continued
washing of jeans causes the dye to rub off and exposes the white cotton
underneath. Jeans fade in a unique pattern, he said, because in their
manufacture, the motion of pulling the jeans through a machine causes
inconsistent bumps along the seams.
Nightingale and Farid sought to test photographic pattern
analysis, involving matching crime scene photographs with wear on blue jeans.
The researchers bought 100 pairs of used blue jeans from thrift stores and
second-hand shops. They photographed the jeans and had images supplied of more
than 100 additional pairs of jeans.
The researchers took photographs of the jeans under various
conditions and found a substantial error rate. According to Ars Technica, “this
means the technique of matching up jeans is likely to be pretty hit and miss -
not catching actual similarities a lot of the time and possibly throwing up a
high rate of false alarms. And that’s under controlled experimental conditions
using high-quality images and jeans laid out nice and flat, not grainy security
footage showing jeans being worn.”
Farid told ProPublic, “If you’re willing to tolerate that
only one in four times this will be useful, OK, fine, use the analysis.”
Last fall, Washington Post Columnist Radley Balko, cited a
1999 Chicago Tribune article to explain the dubious process of blue jean
matching. He also suggested that part of the blame lies with his colleague’s
lack of skepticism - taking the claims of forensic analysts at face value.
Brandon Garrett, a Duke University law professor who studies
the reliability of forensic science, told ProPublica, “This is one of many
studies uncovering non-trivial error rates for forensic techniques,” he
continued, “Any lawyer or any judge in a case involving this discipline should,
at minimum, hear about the error rates. Many people assume that these
techniques are perfect.”
Judges, lawyers and jurors cannot blindly accept that a new
investigative technique lives up to the hype. Just as with journalists, a heavy
dose of skepticism is the best practice.
Matthew T. Mangino is of counsel with Luxenberg, Garbett,
Kelly & George P.C. His book “The Executioner’s Toll, 2010” was released by
McFarland Publishing. You can reach him at www.mattmangino.com and follow him
on Twitter at @MatthewTMangino.
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