Tool, Tire, and Tread Marks/Firearms P1

Question 1

Toolmark

Answer 1

any cut, impression, scratch, or abrasion created by a tool acting on a softer surface or object

Question 2

Source of a toolmark

Answer 2

the object that made it

Question 3

Substrate

Answer 3

the surface or material in which the toolmark is made

Question 4

Compression

Answer 4

occurs when a tool makes direct contact with a softer substrate

Question 5

Sliding

Answer 5

occurs when the tool moves along the surface of the substrate

Question 6

Cutting

Answer 6

occurs when a tool is used in an attempt to perforate through the substrate

Question 7

If enough force is applied,

Answer 7

the impression of the tool is made as the surface of the substrate is compression

Question 8

Sliding usually results in

Answer 8

a series of parallel striations

Question 9

Cutting is a combination of

Answer 9

compression and sliding

Question 10

Ways of collecting toolmarks

Answer 10

Collect the object with the toolmark.
Cut the toolmark area from the object.
Make a cast of the toolmark.

Question 11

Casts of toolmarks are usually made with….

Answer 11

Mikrosil

Question 12

The variations of non-firearm related toolmarks can be separated into

Answer 12

orientation of the object, force, substrate type, and number of marks

Question 13

What is typically used for making casts of shoe and tire impressions

Answer 13

Dental stone

Question 14

How are dust prints deposited?

Answer 14

When a foot or shoe becomes contaminated with a foreign material and that material is transferred onto a surface

Question 15

Rubber lifter

Answer 15

uses a sticky surface and is placed over the print, then lifted from the surface

Question 16

Photographic paper method

Answer 16

involves laying black or white photo paper (depending on the colors of the surface and print) onto the print surface

Question 17

Electrostatic Lifting Apparatus

Answer 17

produces a mirror image of the processed print

Question 18

Characteristics in the tire impression that should be noted

Answer 18

Tread design
Wear bars
Noise treatment
Accidental marks or variations

Question 19

Wear bar

Answer 19

a raised rubber bar 1/16 of an inch above the base of grooves on a tire

Question 20

Tread design

Answer 20

the part of the tire that contacts the road and has a design specific to a model of tires

Question 21

Accidental marks/variations

Answer 21

specific marks created either in the manufacturing process or by the process of wear

Question 22

Where are three dimensional shoe impressions generally made?

Answer 22

Soft exterior surfaces, dirt

Question 23

When a crime scene impression corresponds in both design and physical size of that design with the suspect’s shoe, the association has a ___ evidentiary value

Answer 23

high

Question 24

_______ impressions are collected from victims, police officers, or medical personnel so that they can be accounted for if similar impressions are found at the scene

Answer 24

Elimination

Question 25

A footwear impression of what origin can be lifted using electrostatic lifting?

Answer 25

Dry

Question 26

The _____ track width will always record accurately, so this tire track should always be obtained at crime scene

Answer 26

Rear

Question 27

Sometimes a ______ is used to help visualize impressions for digital imaging

Answer 27

Developing Reagent

Question 28

What kind of lighting can be used to search for faint impressions?

Answer 28

Oblique Lighting

Question 29

The main features that distinguish one pair of shoes from others of the same size and style are collectively called ____________

Answer 29

Accidental Marks

Question 30

SoleMate® is an example of a _____ of shoeprints

Answer 30

commercial database

Question 31

Dental stone can be used in snow, but only if _____ is applied first

Answer 31

Insulating wax

Question 32

When comparing impressions, what area is normally the first aspect to be examined?

Answer 32

Sole design

Question 33

2D impressions

Answer 33

Indoors, hard surfaces

Question 34

3D impressions

Answer 34

Plastics; outdoors in soft surfaces

Question 35

What methods are used to enhance footprints?

Answer 35

Oblique lighting and LCV

Question 36

Impressions

Answer 36

Show tread design and dimensional features of individual tires

Question 37

Tracks

Answer 37

Shows relationships between tires

Question 38

Deposition of rubber tells us

Answer 38

The vehicle was skidding

Question 39

Tire tracks give us….

Answer 39

Track width Turning diameter Path history

Question 40

What are some ways we can collect tire impression evidence?

Answer 40

Examination photograph Cash with dental stone

Question 41

Exemplars of tire treads are always..

Answer 41

2D

Question 42

What are class level characteristics of tire tread marks?

Answer 42

Number and shape of ribs Slant and size of grooves Arrangement of design elements

Question 43

For flat objects, we need ____ for an identification

Answer 43

one group of 8 CMS or 2 groups of 5

Question 44

What should be analyzed with the comparison microscope?

Answer 44

very small items

Question 45

When analyzing shoe prints, there may be a gap between the front and back of the impression, due to a structure called the

Answer 45

shank

Question 46

How should dust footprints (on smooth surfaces) be collected?

Answer 46

ESLA & gel lifter

Question 47

3D casts of footwear - either exemplars or evidence - are made with _________________

Answer 47

dental stone

Question 48

Which of the following methods would be ideal for identifying the source of a footprint?

Answer 48

Comparing a ESLA dust lift to an inked exemplar

Question 49

Place the steps of tire impression casting in the correct order

Answer 49

Photograph the impression, overlapping as necessary Prepare the mold and liquid dental stone Pour the dental stone into the mold Mark with caster's initials or ID # Allow to harden completely

Question 50

Tire analysis is different from footwear analysis in which way?

Answer 50

Tires are most frequently compared using a 2D exemplar to a 3D casting

Question 51

Class characteristics are more difficult to determine from ____ tool marks than other types

Answer 51

sliding

Question 52

What components of a firearm can mark a cartridge case in forensically useful ways?

Answer 52

Firing pin Ejector Breechblock or Breechface

Question 53

caliber

Answer 53

approximate diameter of a rifled barrel

Question 54

Compared to other types, _____ bullets are best marked by the rifling of a barrel

Answer 54

lead

Question 55

A comparison microscope consists of two light microscopes connected by a(n): __________

Answer 55

optical bridge

Question 56

What force typically moves the slide or breechblock back to the cocked position after a semiautomatic pistol is fired?

Answer 56

Energy produced by the fired cartridge

Question 57

Shooting distance determination depends on comparing the ________ on artificial targets to the evidence collected at the scene

Answer 57

residue distribution

Question 58

Elimination and comparison images are collected using

Answer 58

compressible foam

Question 59

Stance

Answer 59

track width

Question 60

wheelbase

Answer 60

measurement between the centers of the hubs of the front wheels to the centers of the hubs of the rear wheels