Indelible Evidence

Even on spent cartridges traces of the criminal remain

The discovery by chemist John Bond from the University of Leicester could revolutionize criminology and force law enforcement agencies to look into many leads. A scientist, at the request of the local police, has developed a new method for detecting fingerprints. It turns out that there are objects from which traces of capillary lines simply cannot be erased with any rag. Even fire cannot burn out ordinary stains of grease and sweat that are not visible without a strong magnifying glass.

Leicester chemists decided to find out what our hands can do with metal. For example, with ammunition for firearms. It turned out that our fingers are not such a harmless thing. It is enough to grasp the cartridge once (for example, driving it into the magazine), and the metal of the cartridge case will immediately begin to rust. Iron oxides form on its surface, in the place where particles of fat and sweat from our hands have fallen. This, of course, will not harm the cartridge, but a criminologist with proper skill can detect the touch.

Bond discovered that fingerprints on metal are virtually indestructible. The same sleeve can even be thoroughly washed with a washcloth and soap in hot water, but the rusted rings and curls of our capillaries will remain intact. Oxides, apparently, can only be removed with sandpaper or a file. But they are completely unafraid of gunpowder fire and smoke: you can even remove your fingers from a spent cartridge case.

The technique described by the team of agent 007's namesake is simple to the point of triviality. In order for evidence to appear on the metal of the shell, you need electricity and a fine powder, such as that used in photocopiers. Under the influence of an electric charge, dust particles line up and show rust stains. Such a print can be taken not only from iron, but also from objects made of other metals and alloys.

Of course, the technique must be described and tested properly. And then you will have to convince criminologists that this method is no worse than traditional methods of identifying fingerprints. But if Bond’s technique begins to be accepted in courts as evidence, the criminals will be in trouble, since any spent cartridge case found at the crime scene will help identify the attacker. And it will certainly be extremely risky to throw a weapon at the scene of a contract murder: after all, no matter how you wipe it, even one accidental touch to the metal will leave an indelible mark and give the investigator a chance to pin down the killer. And careful criminals will probably now carefully collect all their cartridges. After all, they will be able to point out not only the model of the pistol.

The University of Leicester suggests that John Bond's technique could provoke a review of old criminal cases. After all, the chemist claims that fingerprints leave almost “eternal” rust on the metal. This means that even evidence that has been stored in the archives for several years can still point to a suspect.

Vladimir DZAGUTO