TOOL MARK
IDENTIFICATION
Tool
An object used to gain
mechanical advantage.
Also thought of as the
harder of two objects
which when brought into
contact with each other,
results in the softer one
being marked.
Tool Marks
Any impression, abrasion, or cut made
when contact occurs between a tool and
an object
 Even mass-produced tools have minor
differences that can differentiate one tool
from another (Recall the differences
between class and individual
characteristics)

Types of Tool Marks
Indentation Marks: made
when a tool is pressed against
a softer surface; this mark is a
negative impression of the tool;
ex: screwdriver on wood
 Abrasion Marks: made when
surfaces slide across one
another; ex: pliers or knives; the
harder surface leaves scratch
marks or striations on the softer
surface
 Cutting Marks: produced
along the edge as a surface is
cut; ex: saw or wire cutters

Tools – Classification


Tools can be classified according to type of action it
imparts on the work piece. The action affects the
marks left on the work piece.
Examples of different types of actions include:
 Compression
 Flat Action
 Gripping
 Shearing
 Slicing
Tools - Compression

Compression tools are
designed to compress by
pressure or impact. These
tools include hammers,
chisels, and die stamps.
Tools – Flat Action

Flat action tools work in
parallel to the working
surface. These types of
tools include screwdrivers,
pry bars and tire irons.
Tools – Gripping Action

These tools use
opposing jaws to
squeeze or hold an
object. Tools in this
category include vise
grips, tongue and
groove pliers, and pipe
wrenches. They are
also called serrated
jaw gripping tools.
Tools - Pinching Action
These tools use opposed jaws
which are designed to cut using a
pinching action. Examples of
these types of tools include bolt
cutters and diagonal cutters.
Tools – Shearing Action
Shearing tools use two blades
on adjacent planes that pass by
each other and are designed to
cut. These types of tools
include scissors, tin snips, wire
cutters, and pruning shears.
Tools – Slicing Action

Slicing tools cut materials
by moving a sharp blade
along the direction in which
it is traveling. These tools
include knives and razors.
Documenting Tool Mark Evidence—
Photography
Photograph all the evidence with a
measuring device to show appropriate
scale for reference
 Use oblique lighting because it casts
shadows and highlights details that are
not easily visible under direct light

Documenting Tool Mark Evidence—
Casting



If possible, the piece of
wood, metal, etc. that has
the tool mark evidence
should be removed and kept
as evidence
If not possible, a cast
impression should be made
using silicone or rubberbased casting materials such
as Mikrosil
Be sure to dust for prints
before making a cast
Test Marks
Several types of tools are tested to see if
they can make a similar mark
 By comparing the crime scene tool marks
with the test marks, the kind of tool used
in the crime can be determined
