Clued
up for crime-solving
January 20,
2006
Victoria
Neumark finds out how to catch criminals
"If we're going
to prove I was in the room and I'm going to help you, I'd
better put on my lab coat," says Malcolm Rose, analytical
chemist, author of books on mass spectrometry and inventor
of the popular Traces series of teen crime novels, launched
this year.
There is a gasp at the coat's red splotches, which he avers
with a twinkle, are blood spots from an accident he had to
stop and analyse en route to the Lord Grey School,
Bletchley, today. Seriously, though, these were just felt
pen stains. But how can forensic scientists help with crime
detection? And for how long has this young volunteer been
left as a "dead body" on the classroom floor? The answer,
involving rigor mortis ("He'll be cooling down soon," calls
out one Year 9 girl), insects and decomposition is, says
Malcolm Rose, an example of the "apparently awful way in
which nature recycles elements of the body". It's also a
striking way to illuminate some key scientific concepts on
a wet Friday afternoon.
When we move around the world, what traces do we leave
behind us? And how do scientists track them? As Malcolm
Rose goes through the evidence he has left behind in his
20-minutes' worth of talking about being an author, eyes
widen and hands shoot up. "When is a glass of water more
than a glass? When is it a clue?" "Sir, you left your
saliva on the glass." "Which means?"
"DNA."
Three little letters for a massive concept, but the
children seem to grasp it - sequencing, the stuff of life,
chemical markers - just as they go beyond the notion of
fibres snagged from trousers and focus on the differences
between polymers and natural fibres in clothing. And then
there is the cough and sneeze.
They get those, but are suitably revulsed to hear that a
cough travels at 60mph and a sneeze at 100mph: speeding
snot, yuck! A theatrical wipe of the hand and splatter of
sweat from a heated brow has been noted by the eagle-eyed
bunch in the front row, who are even more revulsed to learn
about possible toilet clues and intimate DNA material.
Then there's that muddy shoeprint. The pattern and shape
says a lot about Malcolm's footwear and analysis of the
soil can reveal where he's been.
"Near the end, you scratched your head." "So?" "You'll have
left some hairs and skin." "Well spotted. And very polite.
You didn't call me an old balding bloke with dandruff."
That's more DNA left behind in the classroom.
This is problem-solving at its most technical, with a plea
to work out how to salvage writing impressions from an
apparently blank pad. By scraping graphite from a pencil
over the pad and brushing lightly, words can be read - do
it yourself at home.
One of the most interesting parts of the workshop for
science teachers comes with a discussion of fingerprinting.
Fingerprints have, according to research printed in New
Scientist, never been scientifically validated (for
accuracy). Their rate of error has never been determined in
the 100 years in which they have been used, though
individuals have had judgments reversed when fingerprint
evidence has been shown to be distorted or partial. As
Malcolm Rose points out, partial prints are inevitable. A
glass, for instance, is curved yet the pads on fingers are
more or less flat. Most prints on curved surfaces,
therefore, are somewhat partial.
Which leads very nicely, considers Philip Owens, head of
science at Lord Grey, to a consideration of scientific
error and how accounting for error is integral to
scientific investigation and method.
Another common bugbear in science is communication. The
Traces books, set in a parallel England, feature a robot,
Malc (Mobile Aid to Law and Crime) who cannot understand
figurative language. So if you tell him "I smell a rat"
he'll reply: "There are no odours indicative of vermin."
Getting pupils to discuss unambiguous expression is very
valuable. More valuable is reinforcing that basic truth
that humans are by nature scientists and that "science is
applied curiosity". Or, as Year 9 at Lord Grey put it, that
was "dead good".
* Malcolm Rose's third book in the Traces series is Roll
Call, Kingfisher Books £5.99.
Email:
malcolmrose@talk21.com www.malcolmrose.co.uk
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