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 MUGSHOTS

Soon, a drop of blood could provide forensic scientists with all the information they need to draw the mugshot of a suspect. Researchers are starting to establish how our genes shape our faces, and if they manage to hone their techniques enough, it would mean that they could recreate a person’s visage from a tiny DNA sample. Dr Mark Shriver, an anthropologist at Pennsylvania State University, is on the case. Working with Dr Peter Claes, an imaging specialist in Belgium who captured three-dimensional images of over 600 volunteers’ faces, he analysed a bunch of genes and was able to pinpoint 24 versions, or ‘ variants’, of 20 genes that would help with predicting someone’s facial shape.

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 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.

SCENT OF A VILLAIN

In the future, could vanishingly small traces of perfume or aftershave on a shirt could be enough to bring an attacker to justice? Fragrances are notoriously difficult to detect because they are made up of volatile molecules that evaporate rapidly. But a team led by PhD student Simona Ghergel at University College London has found that the cocktail of compounds that make up perfumes can be transferred between clothes and subsequently detected. The highly-sensitive detection technique is known as ‘gas chromatography-mass spectrometry’. In one test, when two fabrics had been in contact for just one minute, 15 out of 44 fragrance components in a male cologne were found.