Tool marks

Question 1

What does the tool mark examiner do?

Answer 1

identification and comparison of tools
physical fit
firearms examination
recovery of trace evidence

Question 2

What situations are tool marks found?

Answer 2

burglaries

forced entries

Question 3

What is modus operandi?

Answer 3

when people e.g. burglar has a favourite method of entry influenced by past experiences

Question 4

What two factors do offenders look for in a tool?

Answer 4

portability, e.g. JCB good but not portable

efficiency = what works vs what is concealable

Question 5

Tool examples

Answer 5

crowbar
hammer
bolt cutters
chisels
screwdrivers
saws
drills

Question 6

Name 4 tools in the Leverage category?

Answer 6

crowbar
chisels
screwdrivers
claw hammer

Question 7

Name 2 tools in the splitting or parting category?

Answer 7

chisels

screwdriver

Question 8

Name 2 tools in the breaking/smashing category?

Answer 8

hammer

sledgehammer

Question 9

Name a tool in the boring tool category?

Answer 9

drills

Question 10

Are marks left in soft or hard material more likely to yield useable mark of value?

Answer 10

soft

Question 11

What are cylinder locks subject to?

Answer 11

floyding

Question 12

What kind of photography is used to document marks before casting?

Answer 12

macro

Question 13

What are casts usually made from?

Answer 13

Mikrosil

Question 14

What is an impression/imprint tool mark?

Answer 14

static mark made when an object presses into another causing imprint
leverage marks
hammer imprints

Question 15

What is a striated tool mark?

Answer 15

dynamic mark made when objects slide across eachother
harder object will tend to scratch or deform the softer
cutters or snips
splitting or partingtools
complex to examine

Question 16

What is a crush tool mark?

Answer 16

when an object presses into another causing crushing and deformation
cutters

Question 17

What is a multistroke tool mark?

Answer 17

saws

files

Question 18

Bolt cutters

Answer 18

case hardened steel
used on dadlocks and chains
squeezes until metal gives way

Question 19

What are striations?

Answer 19

ridges and furrows formed by metal-metal dynamic contact

positions and intensity related to the microscope characteristics of tool

Question 20

Test marks

Answer 20

marks should be made in same manner as scene mark
be produced in an identical/similar material
treated with same manner as scene mark

Question 21

What are class characteristics (level 1)?

Answer 21

repeatable characteristics shared by many tools of the same type or class
planned characteristics
-length
-width
-shape

Question 22

What are sub-class characteristics (level 2)?

Answer 22

characteristics shared with a more limited set of tools of the same type or class
characteristics relating to manufacture on a specific machine
-stamping
-die casting
-polishing

Question 23

What are identifying characteristics (level 3)?

Answer 23

characteristics found in only one tool

• randomly obtained
• microscopic detail
• specific damage
• broken fragments

Question 24

Comparison microscopy

Answer 24

allows overlap or superimposition of the two images produced

normally 10-20x magnification for forensic work

Question 25

Name 5 techniques used for paint analysis.

Answer 25

SEM
pyrolysis GCMS
solvent testing
FTIR
MSP

Question 26

Name 2 techniques used for glass analysis.

Answer 26

GRIM

Chemical analysis

Question 27

What are the 4 conclusions that can be made with tool marks?

Answer 27

1) mark made by examined tool
2) marks consistent in class characteristics and show a number of other similarities
3) marks are clearly different
4) marks not sufficiently clear

Question 28

Issues with tool marks

Answer 28

relies on finding victim with tool in question
tools discarded during attempted escape
marks often indistinct