Australian_Geographic_2015_07-08.

July–August 2015 47

well. 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 INT

What you’ve touched (including

gunpowder residue, explosives or

even poisons potentially associated

with a murder).

1 What you ate within the past hour.

2

3

The reality is there isn’t much

you can do now that someone

won’t be able to trace afterwards.

Continued page 50

BALLISTICS

1

2

3

Close 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:

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