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Forensics > Fingerprints > Flashcards

Fingerprints Flashcards

1
Q

What is a known fingerprint called?

A

An exemplar

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2
Q

What are friction ridges?

A

Raised portions of the skin (corrugated formations) consisting of one or more connected ridge units of friction ridge skin
Also known as epidermal ridges, papillary ridges and rugae

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3
Q

What are the characteristics of friction ridges?

A
  • permanent
  • unchanging
  • unique
  • form at 12-16 weeks gestation (foot 1 week later than hand)
  • even identical twins have different friction ridges
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4
Q

What are the purposes of friction ridges?

A
  1. Enhance tactile sensitivity

2. Increase pad friction

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5
Q

What are ridge patterns classified by?

A
  • general shape
  • position within the digit
  • relative size
  • minutiae
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6
Q

What is a delta?

A

The point nearest the centre of the divergence of the type of lines

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7
Q

What is the core?

A

The innermost position of concentric or loop ridges

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8
Q

What is a ridge end?

A

Where individual ridges come to an end

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9
Q

What is a bifurcation?

A

Where a ridge divides into 2 ridges

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10
Q

What is an island?

A

Any short ridges cut off from others

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11
Q

What is a crossover?

A

Where any ridges appear to cross over each other

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12
Q

Loop pattern

A
  • ridges flow in one side, loop around, touch an imaginary line drawn from the delta to the core, and exit on the same side from which it has entered
  • has only one delta
  • account for 60-70% of fingerprints
  • 2 types: ulnar loops and radial loops
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13
Q

Whole pattern

A
  • a series of a,most concentric circles
  • has 2 deltas
  • account for 25-35% of fingerprints
  • 4 types: plain whorl, central pocket loop whorl, double loop whorl, accidental whorl
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14
Q

Arch pattern

A
  • in an arch pattern, ridges flow in one side and out the opposite
  • no deltas
  • account for 5% of fingerprints
  • 2 types: plain arch and tented arch
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15
Q

What are fingerprints useful for?

A
  • latent print comparison
  • national police checks
  • deceased identification
  • immigration
  • biometric analysis
  • electronic security
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16
Q

Mummification and fingerprints

A
  • naturally desiccation can occur where the moisture contents of the tissues is below the level, required for bacterial putrefaction
  • fingerprints can be restored from a mummified cadaver through boiling and other processes
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17
Q

What is maceration?

A

Changes to the skin resulting from prolonged exposure to water or moisture

18
Q

What occurs during maceration?

A
  • epidermis becomes disconnected from the der,is
  • softened and loosens
  • thickens
  • becomes wrinkled and white
  • exfoliation of the epidermal glove (epidermis disconnected)
  • the maceration of a corpse is still useful for fingerprint identification
19
Q

What is congenital polydactyly?

A

Growth of extra digits

20
Q

What is syndactyly?

A

Joining of the fingers

21
Q

What is zygodactyly?

A

Webbing or the fingers or toes (also known as incomplete syndactyly)

22
Q

What is ridges-off-the-edge (Cuspal patterns)?

A

The ridges of the digits flow upwards rather than form whorls or loops (usually classified as tented arches)

23
Q

What is ridge hypoplasia?

A

Ridges are reduced in height, often combine with and excess of ‘white lines’ on the prints

24
Q

What is ridge aplasia (adermatoglyphia)?

A

Inherited absence of epidermal ridges

25
Q

What are dissociated ridges?

A

Ridges form, but do not consolidate into continuous ridges

26
Q

What are split ridges?

A

Spacing between the ridges is larger than usual, giving the appearance of being split or paired

27
Q

What is a fingerprint?

A

A reproduction on a surface of palmar or plantar friction ridges

28
Q

What is a latent fingerprint?

A

Made in perspiration (or other clear foreign matter such as grease form hair oil) and is not readily visible until developed

29
Q

What are visible (patent) fingerprints?

A

Made in paint, blood or other foreign matter and are easily visible to the human eye

30
Q

What are moulded fingerprints?

A

Made in a soft substance such as putty, dust, thick grease or wax etc. also known as plastic prints

31
Q

What are etched fingerprints?

A

Where the acidic nature of perspiration has eroded into a soft metal such as brass or copper

32
Q

What has to happen for a print to occur?

A
  1. A sufficient amount of perspiration (or contaminant) must be transferred from the ridge skin to the surface on contact
  2. The surface must not destroy or dissipate the fingerprint deposit (I.e. not excessively dirty, wet, heavily textured etc)
  3. The perspiration (or skin matter) must have a sufficient lifespan (I.e. remain present long enough to be discovered)
33
Q

What are the factors that affect the lifespan of a print?

A
  1. Composition
  2. Amount
  3. Receiving surface
  4. Position
  5. Environment
  6. Time
34
Q

How are surfaces onto which fingerprints are deposited divided?

A

Porous and non porous

35
Q

What is the most common developer?

A

Powder

36
Q

What is the identification methodology?

A

ACE-V

37
Q

What does ACE-V stand for?

A

Analysis
Comparison
Evaluation
Verification

38
Q

Analysis

A

The developed impressions are examined to ascertain if there is enough detail to proceed

39
Q

Comparison

A
  • introduces the exemplar with which the latent print is to be compared
  • analysis of the exemplar also occurs
40
Q

Evaluation

A

3 outcomes:

  1. Identification: unknown impression made by same person as known impression
  2. Exclusion: unknown impression not made by same person as known print
  3. Undetermined: insufficient information in the known or unknown to form and opinion
41
Q

Verify

A

All identifications must be independently verified by a second qualified expert

42
Q

What is the minimum number of matching points required to identify an individuals fingerprints?

A

There is no minimum

Forensics (18 decks)

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