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Sometimes, during a crime, keys or other metallic objects such as guns which are identifiable by a serial number are used. When this happens, a common approach utilised by criminals to try and avoid detection is to attempt to destroy the serial number by scratching it off. This can destroy on otherwise useful line of evidence meaning that the forensic examiner or law enforcement agency has to search for alternative means to solve the crime. However, there is a way to recover it...
When a serial number is imprinted on to a metallic object, it causes disruption to the structure of that metal to a depth greater than the depth of the actual imprint. When someone attempts to scratch away that serial number they would normally only do so until it is no longer visible by eye.
EBSD is able to see uncover what would otherwise be invisible – even to other methods of imaging in microscopy – and image the serial number which the criminal had believed to be destroyed.
This works by looking at the contrast present in the diffraction patterns when the sample is mapped by EBSD. The more deformed a particular point is, the lower the contrast will be. By making an image showing the level of contrast at each point, we can visualise the original serial number.
Back to Forensics & EnvironmentHere, we demonstrate the ability of EBSD to detect otherwise invisible plastic deformation introduced to the sample by the engraving process – allowing the reconstruction of a polished away serial number.
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