July–August 2015 47well. She had been at the department for three years
when the case landed on her desk in 1992.
“I was one of the fi rst to work on the Pia Navida
case,” she says. “It was frustrating. When we
started we had such limited technology that it was
diffi cult to even [know if] the blood under her nails
was her own. But by the time Matthews was arrested,
we’d been able to recover DNA profi les from three
other people.”F
ASS IS THE external facility that conducts the
majority of forensic testing for the NSW Police.
It also helps other states with specialist
examinations from a new $5-million, warren-like
facility in Lidcombe, in Sydney’s west. The secure
lab, surrounded by high fences and surveillance
cameras, is at the cutting edge of detecting
traces of DNA, gunshot residue, explosives and
other chemicals.
“When I started in the ’90s, we needed a blood
stain around the size of a 50-cent piece in order to
be able to sample someone’s DNA,” says Sharon.
“Now we only need 20 skin cells from a sample that’s
so small you wouldn’t even be able to see it. In fact,”
she says, gesturing at my elbow resting on her desk,“you’ve probably just left enough cells right there for
me to generate a DNA profi le.”
It sounds remarkable, but scientists can now work
out the foods you’ve recently eaten, or the drugs you
take, from a fragment of your fi ngerprint; they can
also fi nd clues in every microscopic piece of fi bre or
hair that you leave behind.
Even the microscopic bacteria that live upon your
skin, or – in unfortunate circumstances – the
maggots that end up feasting on your dead body,
can betray your recent movements. The new DNA
technology is so sensitive that I have to provide a
cheek swab before I enter any of the labs in case
one of my shedded skin cells places me at the scene
of a murder.ANALYSING
A FINGER-
PR INTWhat you’ve touched (including
gunpowder residue, explosives or
even poisons potentially associated
with a murder).1 What you ate within the past hour.23The reality is there isn’t much
you can do now that someone
won’t be able to trace afterwards.
Continued page 50BALLISTICS12
3Close inspection.
Dr Jo Bunford examines
car paint that was left
at a crime scene.Any drugs that you’ve taken.Whether it passed through anything else.How far away the shot was fi red.BY STUDYING how The type of gun it was shot from.
a bullet hits its
target, researchers
can work out:EVERYTHING WE consume leaves
chemical traces in our sweat,
which is transferred onto surfaces
along with our skin cells when we
leave a fi ngerprint. Using a
technique known as mass
spectrometry, researchers can
assess the amount and type of
chemicals in that sweat. Although
this research is still in the lab
stage and isn’t yet being used
regularly by police, it can reveal: