Documentation & Trace Analysis

Question 1

Define chain of custody and why it is important.

Answer 1

Chain of custody is the chronological documentation of the movement of the evidence.
Prevents samples from being deemed useless and contaminated in court

Question 2

What is trace evidence?

Answer 2

Occurs when different objects contact one another. Usually evidence not visible to the eye. Can include:
Finger prints
Hair
Cosmetics
Fibres
Soil
Paint
Residue

Question 3

Examples of Trace evidence

Answer 3

Finger prints
Hair
Cosmetics
Fibres
Soil
Paint
Residue

Question 4

What is Locard’s principle?

Answer 4

Every contact leaves a trace

Question 5

What are the methods of collection?

Answer 5

Specific materials all have different collection methods.
Handpicking
Tape Lifting
Brushing/Shaking
Vacuuming
Swabbing
Bagging (beadspace collection)

Question 6

What are the types of paint?

Answer 6

Domestic/architectural

Automotive

Question 7

What kind of cases involve paint examination?

Answer 7

Motor vehicle accidents
Hit and run (car x car or car x other)
Property damage
Break and enter

Question 8

What is a binder?

Answer 8

Coating that allows pigment to distribute across the surface

Question 9

What is a solvent?

Answer 9

It dissolves the binder and allows the paint to have a consistency suitable to use.

Question 10

What is a special-purpose coating?

Answer 10

Coating used to fulfil a specific need and has another purpose other than protection and aesthetic
I.e. waterproofing, skidmarks

Question 11

When does paint transfer occur?

Answer 11

When heat/friction and/or pressure being applied between 2 objects.
Can occur as droplets or spillage

Question 12

Explain what one way and two way transfer of paint occurs.

Answer 12

One way: Vehicle A only transfers paint to vehicle B

Two Way: Vehicle A and B transfer paint onto each other

Question 13

Explain the process of paint examination with Optical Microscopy?

Answer 13

Allows a visual microscopic view of the different layers of paint

Question 14

Explain Infrared Microscopy

Answer 14

Provides information about binder types and fillers/pigments

Question 15

What is UV VIs

Answer 15

It is a tool used to look at pigments as the human eye often cannot distinguish between two closely related colours.

Question 16

What is SEM/EDX?

Answer 16

The elemental and inorganic analysis of paints and coatings.
I.e. aluminium, magnesium detection
-Scanning electron microscopy-energy dispersive X-ray analysis-

Question 17

What is the refractive index of light?

Answer 17

The way light bends and retracts as it travels through glass

Question 18

17. Why type of fibres have low evidentiary value

Answer 18

○ White cotton fibres and blue cotton denim fibres

Question 19

18. How are documents for evidence handled and packaged?

Answer 19

○ Documents, handled with care to preserve their original form and condition
○ Plastic covers/envelopes are used

Question 20

Packaging of Evidence

Answer 20

• Ignitable Liquid residues: air tight tins or cryovac bags. Brown paper bag must NOT be used.
• Glass: not in plastic = mouldy; control samples in plastic pots, not glass vials.
• Globes: protected w cotton wool to preserve damage.

Question 21

19. When are fingerprints detected on document evaluation?

Answer 21

○ After document examination to prevent bleeding of the ink

Question 22

20. How are obliterated document entries revealed?

Answer 22

○ Using optical enhancements

Question 23

How are indented impressions detected on documents?

Answer 23

Electrostatic Detection Apparatus (ESDA).

is used to produce a permanent ‘lift’ from paper which provides a visual map of indented impressions in that paper.

Question 24

21. What are the different types of glass examination used in forensic investigation?

Answer 24

○ Refractive indexes
○ GRIM- Glass Refractive Index
Measurement-compares glass.
○ Inorganic analysis

Question 25

22. How is handwriting analysed and examined?

Answer 25

○ It is analysed using known exemplars and comparing it to the unknown (the document in question) to find matching characteristics in the handwriting

Question 26

23. What are the characteristics found in handwriting?

Answer 26

○	Spacing between letters
○	Spacing between word
○	Relative proportions between letters and within letters
○	Individual letter formations
○	Pen lifts

Question 27

1. What is a single magnifying system?

Answer 27

a. Single lens used to form an enlarged image of an object.

Question 28

2. What is a compound magnifying system?

Answer 28

a. Where magnification occurs in 2 stages.

A compound microscope provides a two-dimensional image, while a stereo microscope provides a three-dimensional image.

Question 29

What methods are used to differentiate fibres?

Answer 29

1. Polarised light Microscopy - Information about the production and finishing of the fibre after spinning.
2. Refractive index- How thick the fibre is.
3. Birefringence- Similar to RI.
4. Fluorescent microscopy- Detecting colour.