Toolmarks

Question 1

What is a toolmark?

Answer 1

The mark which results from the contact of an implement (tool) with a softer surface

Question 2

What is a tool?

Answer 2

The harder of two objects which when brought together into contact with each other results in the softer object being marked
An object used to gain mechanical advantage

Question 3

What is toolmark identification?

Answer 3

An empirical comparative analysis that can determine if a striation or impression was produced by a particular tool (or not)

Question 4

What are the two types of toolmark?

Answer 4

Impressed tool marks
Striation tool marks

Question 5

What is a impressed toolmark?

Answer 5

Compressive force that leaves a compression
E.g. hammer, firing pin, breechface

Question 6

What is a striation tool mark?

Answer 6

Lateral force and motion resulting in scratches across a surface.

Question 7

What are the categories of classes of toolmarks?

Answer 7

Class characteristics
Individual characteristics
Subclass characteristics

Question 8

What is a class characteristic?

Answer 8

Measurable features of a specimen which indicate a restricted group source.
Design features determined prior to manufacture of the tool.

Question 9

What is a subclass characteristic?

Answer 9

Features that may be produced during manufacturing that are consistent among items. Fabricated by same tool in the same approximate state of wear.
More restrictive that class characteristics.

Question 10

Steps when locating toolmark at scene?

Answer 10

1. General photograph, take notes.
2. Barcode toolmarks and re-photograph
3. Take examination quality photographs of marks
4. Mix mikrosil and cast onto toolmarks. Photograph with mikrosil on.
5. Remove mikrosil and re-photograph
6. Take close up photographs of mikrosil cast.
7. If possible seize whole item.
8. Package casts into boxes, seal sign and barcode. Lodge at station.

Question 11

How many mikrosil casts should be made of same toolmark ?

Answer 11

2

Question 12

What do you categories mikrosil cast as on FR?

Answer 12

Mikrosil Cast

Question 13

What items would you collect instead of or as well as casting?

Answer 13

Door handles, wire, chain links

Question 14

When should you collect foreign residue?

Answer 14

Foreign residues need to be sampled prior to toolmark comparison at BU.

Question 15

What is a foreign residue?

Answer 15

Something not original to the tool or toolmark. Example- may be paint transfer from tool to tool mark or vice versa.

Question 16

What material is mikrosil based?

Answer 16

Silicone based

Question 17

What is the questioned toolmark?

Answer 17

The scene one

Question 18

What is the known toolmark?

Answer 18

The test ones being made with the suspect tool

Question 19

What material does the test medium need to be ?

Answer 19

Needs to be a soft material, to not change the tools surface.
E.g. aluminium, wax, lead.

Question 20

What are the conclusions the examiner may come to? Range of conclusions

Answer 20

Identification
Elimination
Inconclusive
Unsuitable

Question 21

Can a toolmark examination be performed through photographs?

Answer 21

No. Must have the item or the casting

Question 22

Can the same FEN be used for both castings of one toolmark ?

Answer 22

Yes

Question 23

What is an individual characteristic?

Answer 23

Marks produced by random imperfections or irregularities of tool surfaces. Produced incidental to manufacture and/or caused by use, corrosion or damage