Lesson 1

Question 1

Evidence

Answer 1

Available facts that are around that can prove the commission of a crime

Question 2

Impression related evidence is based on which principle

Answer 2

Locard’s exchange

Question 3

Impression

Answer 3

An effect of something on another surface

Question 4

Impression evidence

Answer 4

Physical evidence that results for objects / materials retaining the characteristics of other objects through direct contact

Question 5

Pattern evidence

Answer 5

Forensic evidence that can be read and analyzed from a specific type of impression left by physical contact between an object and a surface

Question 6

Importance of pattern evidence

Answer 6

1. Different impressions on a ground could a good pattern on how a particular crime a committed
2. Gives pattern that enables us to know what object created the pattern

Question 7

Types of impressions

Answer 7

1. Patent impressions
2. Latent impressions
3. Plastic impressions

Question 8

Patent impressions

Answer 8

2-D impressions
They are produced when residual substances are transferred from source to a clean surface
e.g. prints in dust, blood, paint,etc

Question 9

Latent impressions

Answer 9

Impressions that are invisible to the naked eye but can be visible using development techniques
Mostly 2-D
e.g. oils, fine soil and other minute debris

Question 10

Plastic impressions

Answer 10

3-D impressions
Impressions can be left in soft materials
Can easily be lost so made permanent through documentation
e.g. snow, mud, soil, soap

Question 11

The quality of the impression depends on:

Answer 11

1. Object making the impression
2. The surface conditions
3. How hard or soft it is
4. Type of material

Question 12

Examples of impression evidence

Answer 12

Bite marks, tyre marks, tool marks, finger marks, footprints

Question 13

Classification of impression related evidence

Answer 13

Imprint
Indentation
Striation

Question 14

Imprint

Answer 14

2-D impression formed as one object transfer materials onto a surface

Latent, patent

Question 15

Indentation

Answer 15

3-D impression formed as an object leaves its surface features on a softer material such as clay, soap, soil/drying blood

e.g. bite marks, footprints in mud, tyre print in clay

Question 16

Striation

Answer 16

Marks created on a softer object when it come into contact with a harder surface during its motion

Commonly observed in fired bullets from a rifle

Question 17

Examination of impression evidence may reveal

Answer 17

— possible number of footwear and/or objects present
— possible sources of what caused the impression
— if an impression was created by a specific object
— manufacturing information about the object creating the impression
— the approximate size of the object creating the impression
— order of deposition and possible movement/direction of travel at the time the impressions were made

Question 18

Impressions can show

Answer 18

1. Class x’tics
2. Wear x’tics
3. Individualizing x’tics

Question 19

Class x’tics

Answer 19

Overall pattern of the shoe outside
The weave of a fabric
The number of ribs and grooves in a tire track

Question 20

Wear x’tics

Answer 20

Those due to erosion of the surface of the item under examination and are reflected in the impression

Question 21

Individualizing x’tics

Answer 21

Products of random events that occur on one item
Allows identification to a specific source
e.g. cuts in shoe outsole, a flaw in the weave of a fabric, a stone in the tire tread

Question 22

Why is impression evidence overlooked and not found

Answer 22

1. Training
2. Scene
3. Other factors

Question 23

Importance of collected impression evidence

Answer 23

To find unique x’tics to link shoes, tires, tools and other objects found in a suspect’s possession to evidence at the crime scene

Question 24

Collection methods

Answer 24

1. Secure and restrict access
2. Detection of original evidence
3. Photography
4. Lifting latent impressions
5. Casting plastic impressions

Question 25

Purpose of securing and restricting access to the crime scene

Answer 25

1. Prevent alterations of the scene 2. Avoid confusion of adding additional prints

Question 26

How can you detect original evidence at the crime scene

Answer 26

Some may be visible, others with the help of oblique lighting and als

Question 27

Als

Answer 27

Alternative light source have filters/combination of filters that allows all but selected wavelength of light to be screened out

Question 28

Photography

Answer 28

Photographs should be taken before any alteration is done to the scene A wide range of view should be taken first, before of the impressions alone and then of the impressions with identifiers and scales

Question 29

If impression is left on a dark surface what should be done for the photograph to be taken

Answer 29

Magnesium smoking is performed leaving a white residue on the surface allowing details of the impression to be visible

Question 30

Lifting latent impressions methods

Answer 30

1. Electrostatic dusting 2. Luminol 3. Dusting 4. Gel lifting

Question 31

Casting

Answer 31

The process used to replicate 3-D impressions/ marks to preserve physical evidence for further analysis

Question 32

Uses of casting

Answer 32

Obtain replicate of tool marks, tire marks, shoe prints Used to record dental x’tics of a body and compare the x’tics with know dental records