2.2.1 The
theory of identification as it pertains to
the comparison of toolmarks enables opinions
of common origin to be made when the unique
surface contours of two toolmarks are in
“sufficient agreement.”
2.2.2 This
“sufficient agreement” is related to the
significant duplication of random toolmarks
as evidenced by the correspondence of a
pattern or combination of patterns of
surface contours. Significance is determined
by the comparative examination of two or
more sets of surface contour patterns
comprised of individual peaks, ridges and
furrows. Specifically, the relative height
or depth, width, curvature and spatial
relationship of the individual peaks, ridges
and furrows within one set of surface
contours are defined and compared to the
corresponding features in the second set of
surface contours. Agreement is significant
when it exceeds the best agreement
demonstrated between toolmarks known to have
been produced by different tools and is
consistent with agreement demonstrated by
toolmarks known to have been produced by the
same tool. The statement that “sufficient
agreement” exists between two toolmarks
means that the agreement is of a quantity
and quality that the likelihood another tool
could have made the mark is so remote as to
be considered a practical impossibility.
2.2.3
Currently the interpretation of
individualization/identification is
subjective in nature, founded on scientific
principles and based on the examiner’s
training and experience.
