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Nr. 91, 15.07.2017  voriger  Übersicht  weiter

On the trail of the truth

If the authorities get stuck with their criminal investigations, science can give them a helping hand. For example, private lecturer Dr Cornelius Courts: the forensic geneticist searches for answers in the smallest molecules.


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A shooting offence usually consists of four elements: a perpetrator, a victim, a weapon and a crime scene. But what happens if not all of these four elements are known, if you only find a gun, for example? Private lecturer Dr Cornelius Courts from the Institute of Forensic Medicine, working together with other researchers, has developed a way to identify the victim and the perpetrator, only on the basis of a weapon.

Sometimes it is the smallest remains, the tiniest traces, which can provide the decisive breakthrough in a criminal case. The research field, which the head of the forensic genetics team has shaped, is called "molecular ballistics". Residues from the perpetrator (such as skin particles which rubbed off when handling a weapon) and the victim can be inspected in detail by the researchers. Of particular importance for molecular ballistics is the so-called back spatter, i.e. residues from a gunshot wound sprayed backwards, against the direction of the shot. These splashes can even land inside the gun.

On the basis of the nucleic acids found inside these splashes (see box), not only can the victim be identified via DNA, but RNA can even be used to determine the point at which the shot entered their body. However, the researchers' results are not always cause for celebration for the police: "Here we work completely independently of the authorities, and do not try to confirm a suspicion - but to find out the truth." If the suspicion cannot be confirmed, the authorities must start over with their investigations.

In times of fake news, the denial of scientific results, and partially religiously-motivated legislation, the truth is not only concealed by the criminals, complains Courts: »On an iPhone, using Twitter, certain politicians type how pointless science is. And are not even aware of the irony.« To counteract this, in his opinion, publicly-funded scientists have a debt to society: »We must explain to people who are interested what we actually do and discover here. And we must do so in a way that is easy to understand.«

Protecting the truth and science is a concern of Courts – not only in the laboratory – he also fights for it in lecture theatres, on the Internet and in public speeches, with great success. With his presentations on genetics, forensics and laboratory work, he was voted »Prof of the Night« at Kiel University's long night of lectures in November 2016, and in April 2017 he won the City of Kiel's Science Slam.

Why is he so successful with his appearances? »I always try to adjust the way I speak to the audience. And I try to find analogies, to make the abstract concepts understandable. It is important that you also admit if you do not know something, or you cannot prove it,« explained Courts.

He also does this on his own science blog, »BlooDNAcid«. Here he discusses topics with his readers such as current research, science policy – or even his taste in music. Because some things in life are beyond true or false, and are excellent for debating!

Sebastian Maas

www.scienceblogs.de/bloodnacid
DNA and RNA
DNA and RNA are nucleic acids. If you imagine DNA, the genetic molecule in the core of every cell, like a library of cookery books and construction plans, then RNA would be like a short-lived copy of an individual book passage or a recipe. With their help, the "factories" in the cell outside of the core get information about what should be manufactured. In liver cells for example, you will mainly find RNA containing information for the synthesis of liver enzymes, but none for the production of stomach acid. On the basis of the RNA, you can therefore determine which part of the body or which organ the human traces originated from.
(sma)
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