|
.jpg)
Tool-marks analysis

Tool-mark analysis is sometimes viewed more as an art and a skill,
then a science. It requires experience, time and patience.
Tool
marks are the "scratches", the striations and the permanent marks
left by the use of a tool against another surface. Tool marks can be
the scratches on a violated door or window, a scratch on a car, or
any solid surface.
In
order to compare tool marks, we have to compare the suspect mark
against some samples, created by known tools. Once a "control" tool
mark matches the suspect, then we know it was that tool that created
the suspect mark. Every tool leaves an individual mark, and is
subject to its usage, tear and wear and even manufacturing
imperfections, previous impacts, etc. The tool mark comparison on
the right is from a comparison test at the University of Strathclyde
forensic laboratories.
Some striations are
more "fancy" and exciting than others. The photo on the right is
from a 9mm Luger case, manufactured by the IMI (Israeli Military
Industries) and it is the same kind of ammo used in the iconic Uzi
automatic machine pistol. Notice the mark at the centre of the
image, created upon the firing of the bullet. Matching bullets seems
more exciting in TV shows like CSI, but it is the exact process used
to match a crow bar or a screwdriver that left a mark on a door.
Strathclyde Forensic makes use of specialty equipment like a
comparison macroscopes to identify and match striations.
|