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Fingerprints can point to guilty person
Theresa Seraphim
for Spotlight
When police process a crime scene, one of their
many tasks is dusting for fingerprints, which can
lead them to the criminal, RCMP Sgt. Bob Dodds
recently told a group of Grade 6 E.G. Wahlstrom
students.
Dodds, who is trained as a scene of crime officer
(SOCO), said when he gets to crime scene he looks
at surfaces that might have been handled by the
potential perpetrator and then gets out his fingerprinting
tools.
Dodds said there are three basic marks on fingers:
whorls (circular pattern), arch (up and down
with sharp curve at top) and loops (up and down
but with a less sharp curve). Each person has 10
different fingerprints.
“They’re all different because they’re formed
while we’re developing in our mother’s womb,”
said Dodds.
“There’s never been a documented case of two
fingerprints the same.”
Most fingers’ patterns go from inside to outside
the finger, while the thumb goes from outside to inside.
This, said Dodds, can narrow down things like a
potential criminal’s handedness.
Fingerprints are made of oil, which is what is left
behind when we touch something, said Dodds, adding
we have fingerprints in the first place to give us
traction when we pick up items.
He brushes the item with a powder, then photographs
them and uses an item with tape in plastic
to lift the prints, after which they are sent to Ottawa
and put into the computer system.
Before digital cameras, photographers used film
to record fingerprints but, said Dodds, because of
the negative image on film, sometimes the print
turned out backwards. Today, each print is marked
with an “R” – because that letter can’t be flipped
backwards – and with the date and the officer’s initials.
Other potential sources of clues are items such
as tire tracks, shoe treads and blood.
“I love a new snowfall,” Dodd says, adding prints
and blood in the white stuff can lead straight to the
criminal.
Dodds recalls a case that occurred when he was
in Fort Nelson where blood was found and sent to a
lab, which determined the culprit because the
match found would occur in only one in 11 billion
people.
Dodds says fingerprinting is easier to do by rolling
the finger outwards rather than inwards. He
says sometimes dead people have to be fingerprinted,
so they can be identified. In that case,
when the skin is receding after death, a needle
with some water is inserted into the finger, and the
water rehydrates the digit.
Hair can be used to extract DNA, but a cheek
swab the best way of getting it, says Dodds.
He says he approaches a crime scene carefully;
looking to see what’s intact or scattered and then,
if necessary, kicking people out and preventing
non-necessary people from getting in.
Avoiding contamination of the crime scene is
key, he says.
“We have to be careful not to touch, not to
sneeze, not to drop anything,” says Dodds.
Even if the perpetrator is determined quickly,
that’s not the end of the case.
“It would still take weeks to prove that this person
committed the crime,” Dodds says, adding that
would involve ballistics, forensics, court date and
sentencing, for a quickest time of six to eight
months.
If the opposite scenario occurs, and there is no
evidence, police are stuck, says Dodds.
“That’s why there are unsolved cases.”
Police find about 30 to 40 per cent of criminals
which, says Dodds, doesn’t sound like much but is
actually a good clearance rate.
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