A peak below the surface…
13 Apr 2015 by hjcmtbbcwq.d hjcmtbbcwq.d
Scientists have designed a technique for recovering destroyed serial numbers on metal objects.
A team of researchers at the National Institute of Standards and Technology in Colorado used a scanning electron microscope to read the crystal structure pattern of damaged metal imprints. They believe that this method could help forensic scientists in reconstructing vehicle identification numbers or imprints on ammunition casings.
“A method which can observe the crystalline structure of materials with very high sensitivity may allow the reconstruction of heavily damaged and destroyed serial numbers. Development of a reliable method for reconstruction of destroyed metal objects is of significant forensic interest,” the scientists said in their paper, published in Forensic Science International.
To recover serial numbers that have been destroyed, the scientists experimented by hand stamping ‘X’ imprints into steel to simulate a serial number imprints. The team then polished away the imprints and used Electron Backscatter Diffraction (EBSD) fitted in a scanning electron microscope to produce an image from the crystal structure.
This technique allowed the scientists to scan electrons over the surface of the crystalline material and produced data showing patterns. Software then generated maps known as pattern quality maps.
The results from these maps revealed the crystal damage and the deformation in the steel that allowed a clear visualisation of destroyed imprints.
“Evidence of the stamp can be observed to a depth of approximately 760 ?m below the surface. With further development, the described method is capable of reconstructing an eight character serial number in approximately 1 h,” said the researchers in their paper.
“Firearm serial numbers are a critical identifying mark, and restoration of destroyed serial numbers is often crucial for prosecution of a criminal case,” the scientists said in their paper.
The technique is still in an experimental stage. The researchers are not sure whether EBSD pattern quality mapping is more sensitive and effective than conventional techniques for reconstructing serial numbers. Experimental comparison is now under way.
Paper: http://www.fsijournal.org/article/S0379-0738(15)00057-2/abstract
