Examination of Firearms Review: 2007 to 2010 - Interpol

Another case of document examination involving physical match was presented by
Brown and Sin-David (124), dealing with the remains of the late Israeli astronaut,
Colonel Ilan Ramon, crew notebook, found in NASA’s Space Shuttle Columbia
crash site. One of the methods applied while studying these exhibits was
physically matching torn pieces of paper found in deferent locations. It should be
noted in this case that the remains had undergone traumatic conditions and tears
of the notebook pages did not show perfect physical matches as expected for
paper torn under laboratory conditions.
5. Restoration of Obliterated Marks
Visualization of obliterated serial numbers, in chassis and engine of vehicles, in
firearms frames and in other objects, may provide important forensic evidence
during criminal investigations, when stolen items have their serial numbers
obliterated in an attempt to conceal their identity or origin. Several articles have
been published during this Review period, regarding methods dealing with this
issue. In addition, updated information and procedures may now be found on the
Internet (4, for example).
The methods applied for such examinations may be divided usually into two
groups (125): Non-destructive methods (like magnetic particles, Eddy current or xray
radiography), and destructive methods (like chemical and electrochemical
etching or thermal annealing). The appropriate method, or combination of
methods, suitable for each surface, is dependent mainly on the surface
composition and manufacturing history, on the marking methods and on the
obliteration process. Many metallurgical tests may be required for each type of
exhibit, for determining the proper procedure to be used.
Weber and Weimar (126) proposed an approach for numerically simulating the
marking process, thus reducing the number of actual metallographic experiments
needed for developing a method for the marking restoration. The finite element
method (FEM) simulation results were compared with actual metallographic
experiments, with comparable results. These authors showed that the FEM
simulation of the marking process is possible, and that the results of such
simulations can be applied to metallographic examinations.
Collaborative Testing Services (CTS) has just recently distributed their first
proficiency test on the restoration of obliterated marks (Test No. 10-525). The final
report, available over the Internet, includes a list of methods used by the
participating laboratories (127). It is interesting to see that many laboratories used
the magnetic particles method, prior to, or instead of, using chemical etching.
5.1 Steel surfaces
One of the most active groups in research in this field is led by Prof. Kuppuswamy,
at the School of Health Sciences, Universiti Sains Malaysia. Following the work by
Zaili, Kuppuswamy and Harun (128), reviewed in our previous Review (1), Yin and
Kuppuswamy (129) studied several common reagents for the restoration of
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