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Intro To Forensics > Tool, Tire, and Tread Marks/Firearms P1 > Flashcards

Tool, Tire, and Tread Marks/Firearms P1 Flashcards

1
Q

Toolmark

A

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

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2
Q

Source of a toolmark

A

the object that made it

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3
Q

Substrate

A

the surface or material in which the toolmark is made

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4
Q

Compression

A

occurs when a tool makes direct contact with a softer substrate

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5
Q

Sliding

A

occurs when the tool moves along the surface of the substrate

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6
Q

Cutting

A

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

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7
Q

If enough force is applied,

A

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

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8
Q

Sliding usually results in

A

a series of parallel striations

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9
Q

Cutting is a combination of

A

compression and sliding

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10
Q

Ways of collecting toolmarks

A

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

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11
Q

Casts of toolmarks are usually made with….

A

Mikrosil

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12
Q

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

A

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

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13
Q

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

A

Dental stone

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14
Q

How are dust prints deposited?

A

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

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15
Q

Rubber lifter

A

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

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16
Q

Photographic paper method

A

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

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17
Q

Electrostatic Lifting Apparatus

A

produces a mirror image of the processed print

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18
Q

Characteristics in the tire impression that should be noted

A

Tread design
Wear bars
Noise treatment
Accidental marks or variations

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19
Q

Wear bar

A

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

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20
Q

Tread design

A

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

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21
Q

Accidental marks/variations

A

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

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22
Q

Where are three dimensional shoe impressions generally made?

A

Soft exterior surfaces, dirt

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23
Q

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

A

high

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24
Q

_______ 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

A

Elimination

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25
Q

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

A

Dry

26
Q

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

A

Rear

27
Q

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

A

Developing Reagent

28
Q

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

A

Oblique Lighting

29
Q

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

A

Accidental Marks

30
Q

SoleMate® is an example of a _____ of shoeprints

A

commercial database

31
Q

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

A

Insulating wax

32
Q

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

A

Sole design

33
Q

2D impressions

A

Indoors, hard surfaces

34
Q

3D impressions

A

Plastics; outdoors in soft surfaces

35
Q

What methods are used to enhance footprints?

A

Oblique lighting and LCV

36
Q

Impressions

A

Show tread design and dimensional features of individual tires

37
Q

Tracks

A

Shows relationships between tires

38
Q

Deposition of rubber tells us

A

The vehicle was skidding

39
Q

Tire tracks give us….

A

Track width
Turning diameter
Path history

40
Q

What are some ways we can collect tire impression evidence?

A

Examination photograph
Cash with dental stone

41
Q

Exemplars of tire treads are always..

A

2D

42
Q

What are class level characteristics of tire tread marks?

A

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

43
Q

For flat objects, we need ____ for an identification

A

one group of 8 CMS or 2 groups of 5

44
Q

What should be analyzed with the comparison microscope?

A

very small items

45
Q

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

A

shank

46
Q

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

A

ESLA & gel lifter

47
Q

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

A

dental stone

48
Q

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

A

Comparing a ESLA dust lift to an inked exemplar

49
Q

Place the steps of tire impression casting in the correct order

A

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

50
Q

Tire analysis is different from footwear analysis in which way?

A

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

51
Q

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

A

sliding

52
Q

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

A

Firing pin
Ejector
Breechblock or Breechface

53
Q

caliber

A

approximate diameter of a rifled barrel

54
Q

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

A

lead

55
Q

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

A

optical bridge

56
Q

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

A

Energy produced by the fired cartridge

57
Q

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

A

residue distribution

58
Q

Elimination and comparison images are collected using

A

compressible foam

59
Q

Stance

A

track width

60
Q

wheelbase

A

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

Intro To Forensics (19 decks)

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