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FORB201 > Lecture 14 - Fingerprints > Flashcards

Lecture 14 - Fingerprints Flashcards

1
Q

Why are fingerprints most practical and regularly found?

A

As humans, we have to touch things

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2
Q

What are 2 important biological principles that fingerprint identification relies on?

A
  • Permanence
  • Uniqueness
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3
Q

How early are fingerprints formed?

Permanence

A

First few months of foetal life (usually around 8 weeks)

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4
Q

For how long will fingerprints be unchanged?

Permanence

A

Throughout life until after death and decomposition sets in

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5
Q

In what instance may the friction skin change or be altered?

Permanence

A

Growth and scarring

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6
Q

Where are ridge units developed?

Uniqueness

A

In the womb

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7
Q

What are ridge units subject to within the womb?

Uniqueness

A

A variety of physical and genetic pressures

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8
Q

What effect does the pressure on ridge units within the womb have?

Uniqueness

A

Variable growth which causes random, unique ridge features

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9
Q

What do the precise shape and orientation of the ridges depend on?

A
  • Position relative to the nail bed and joint crease
  • Size and shape of volar pad
  • Asymmetrical volar pads produce asymmetrical ridge patterns
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10
Q

What are the 3 main pattern types?

A
  • Arch
  • Loop
  • Whorl
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11
Q

What does a whorl must have?

A

2 deltas

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12
Q

How do we make identifcations?

A
  • Pattern type (arch, loop, whorl)
  • Friction ridge formations (ridge ending, bifurcation, dot)
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13
Q

What are the 3 main ridge formations?

A
  • Ridge ending (ridge comes to a stop)
  • Bifurcation (one ridge splits into two)
  • Dot (one pore unit only)
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14
Q

What are some more properties of a fingerprint looked at for identification?

Appart from the main 3

A
  • Scars
  • Creases
  • Ridge flow
  • Pores (poroscopy)
  • Shape of ridge edges (edgeoscopy)
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15
Q

What is an unknown fingerprint called?

A

Latent

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16
Q

What is a known fingerprint called?

A

Linked

17
Q

Why do you always start with the latent (unknown) fingerprint?

A

Reduce bias

18
Q

What are the 3 outcomes of fingerprint analysis?

A
  • Satisfied match
  • Satisfied unmatch
  • Not enough detail, cannot conclude
19
Q

Sufficient is quantity but also…?

A

Quality, fingerprint must be of good enough quality to examine

20
Q

What is the scientific methodology of fingerprint identification?

A
  • Analysis
  • Comparision
  • Evaluation
  • Verification
21
Q

What is the core of a fingerprint?

A

The inner most part of the whorl

22
Q

What are the 3 categories of fingerprints?

A
  • Latent (not visible)
  • Patent (visible)
  • Plastic
23
Q

What are the properties of a latent (non visible) fingerprint?

A
  • Invisible
  • Sweat, oil, grease
  • Need to develop (e.g. powder, chemical treatment)
  • Negative latent print (e.g. tape)
24
Q

What are the properties of a patent (visible) fingerprint?

A
  • Seen by the naked eye
  • Contrasting surface
  • Contaminated print (e.g. blood)
25
Q

What are the properties of a plastic fingerprint?

A
  • Three dimensional
  • Negative print (e.g. wax, putty, wet paint)
26
Q

What are example of a porous surface?

Surfaces/maerials that naturaly have pores

A
  • Paper
  • Card
  • Plaster
27
Q

What are examples of a non-porous surface?

Hard rigid surfaces with no pores

A
  • Bottle
  • Can
  • Glass
  • Plastic
  • Painted wood
28
Q

What are 2 methods used to collect latent fingerprints off non-porous surfaces?

A
  • Brush and powder
  • Chemical treatment (cyanoacrylate fuming)
29
Q

How does the brush and powder method work?

For non-porous materials

A
  • Fibreglass, feather, squirrel, magnetic
  • Using contrasting powder (black, white, grey, fluorescent)
30
Q

How does the chemical treatment (cyanoacrylate fuming) method work?

For non-porous materials

A

Superglue is heated releasing vapour which adherers to print forming hard white polymer

31
Q

What are 2 methods used to collect latent fingerprints off porous surfaces?

A
  • Magnetic brush and contrasting magnetic powder
  • Chemical treatment (ninhyrdin)
32
Q

How does the chemical treatment (ninhydrin) work?

For porous surfaces

A
  • Reacts to amino acids and develops purple colour
  • Takes 2 weeks
33
Q

What is the process for fingerprint from crime scene to court?

A
  • Fingerprint exhibits go to police fingerprint section
  • Search on fingerprint database
  • Compare to elimination prints (person with legitimate acess, retained only for case then destroyed)
  • Result undergoes peer review process
  • Identification memo issued
  • Investigation carried out by police
  • Prosecution
34
Q

What are 6 fingerprint examination tips?

A
  • Visual search first
  • Assess riska nd hazards
  • Development selection(s), surface nad contrast
  • Handle exhibit carefully, as little as possible
  • Magnifying glass
  • Preservation tape, avoid errors i.e. bubbles under gel/tape

FORB201 (18 decks)

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