Page 52 - BBC Focus - August 2017

CRIME

EXTRAORDINARY EVIDENCE

Even the tiniest scraps of evidence can help to catch a criminal

GUNSHOT FORENSICS
Gunshots ring around a city centre street. One man lies dead in the road and another tells the
police he fired his gun in self defence after being shot at. No one saw what happened. The one
thing the police do have is video footage from a mobile phone, while it doesn’t actually show the
shooting, the sounds of the gunshots have been captured. Dr Robert Maher at Montana State
University is the man to call. By firing assorted weaponry near a semicircle of 12 microphones, he
has developed a database of soundwaves produced by different guns. The aim is to enable
different gun types to be distinguished from a sound recording, helping police unpick exactly
what went on in cases like our shoot-out.

GENETIC SCENT OF

MUGSHOTS A VILLAIN
Soon, a drop of blood could In the future, could vanishingly
provide forensic scientists with small traces of perfume or
all the information they need to aftershave on a shirt could be
draw the mugshot of a suspect. enough to bring an attacker to
Researchers are starting to justice? Fragrances are
establish how our genes shape notoriously difficult to detect
our faces, and if they manage to because they are made up of
hone their techniques enough, it volatile molecules that evaporate
would mean that they could rapidly. But a team led by PhD
recreate a person’s visage student Simona Ghergel at
from a tiny DNA sample. Dr Mark University College London has
Shriver, an anthropologist at found that the cocktail of
Pennsylvania State University, is compounds that make up
on the case. Working with Dr perfumes can be transferred
Peter Claes, an imaging specialist between clothes and
in Belgium who captured subsequently detected. The
three-dimensional images of highly-sensitive detection
over 600 volunteers’ faces, he technique is known as ‘gas
analysed a bunch of genes and chromatography-mass
was able to pinpoint 24 versions, spectrometry’. In one test, when
or ‘variants’, of 20 genes that two fabrics had been in contact
would help with predicting for just one minute, 15 out of 44
someone’s facial shape. fragrance components in a male
cologne were found.

WHAT’S IN A HAIR?
Give a strand of your hair to Dr Glen Jackson at West Virginia
University and he can tell your age, sex, what you eat and how
much you exercise. For police with little to go on from a crime PHOTOS: GETTY X3 ILLUSTRATIONS: VLADO KRIZAN
scene other than a few bits of hair, this information can be
gold dust. Jackson and his team measure the ratio of isotopes
– atoms of the same element with different numbers of
neutrons – within the 21 amino acids found in keratin, the
main component of hair. So far, they have found 15 isotope
ratios that provide a window into who someone is.

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