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Forensic Identification Course > Fingerprint Development and Identification > Flashcards

Fingerprint Development and Identification Flashcards

1
Q

Factors to consider for longevity

A
  • atmospheric conditions - substrate - composition matrix - amount of matrix - contamination
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2
Q

What is the purpose of fingerprint powders?

A

To make latent impressions visible

To create contrast with the background

To enable impression to be photographed

To potentially enable the impression to be lifted

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3
Q

Considerations for developing friction ridge impression

A
  • Monetary value
  • Probability of finding impressions
  • Seriousness of Offence
  • Ability to restore after examination
  • Consider non-destructive methods
  • Beware of damage to surrounding area
  • Presence of foreign material
  • Type of substrate
  • Portability
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4
Q

What is the sequence of FR development?

A

Initial examination > reveal > mark > lift

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5
Q

What is the philosophy of FR identification?

A

Friction ridge identification is established through the agreement of friction ridge formations, in sequence, having sufficient uniqueness to individualize.

ridge to ridge, in sequence, sufficence uniqueness to individualize

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6
Q

What are the four premises of FR identification?

A
  1. Friction ridges develop on the fetus in their definitive form before birth
  2. Friction ridges are persistent throughout life except for permanent scarring
  3. Friction ridge patterns and the details in small areas of friction ridges are unique and never repeated
  4. Overall friction ridge patterns vary within limits which allow for classification
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7
Q

What are keys developments in FR identification?

A

1973 - IAI established. “There is no valid basis for requiring a minimum number of friction ridge characteristics present in two impressions in order to establish positive identification”

1995 - Ne’urim Declaration “There is no scientific basis for requiring a predetermined minimum number of friction ridges features present in two impressions in order to establish a positive identification.

2009 - The IAI resolution. “There currently exists no scientific basis for requiring a minimum of corresponding friction ridge detail information between two impressions to arrive at an opinion of single source attribution.”

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8
Q

What is the ACE-V methodology?

A

A methodology used in the individualization of FR impressions. Analysis, Comparison, Evaluation, Verification

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9
Q

What is the purpose of the Analysis stage of ACE-V?

A

The gathering of objective information regarding the questioned impression.

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10
Q

What are the 7 stages of analysis?

A

Anatomical Considerations

Substrate

Matrix

Development Medium

Deposition Pressure

Lateral Pressure

Clarity

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11
Q

What is considered when analysing anatomical features?

A

Digit determination, pattern, and how the object was handled.

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12
Q

What is considered when analysing substrate?

A

Describe the surface that the impression has been deposited. Are there any characteristics of the substrate that is interfering with th questioned impression.

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13
Q

What is considered when analysing matrix?

A

The material/substaces deposited onto the substrate by the finger(s).

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14
Q

What is considered when analysing development medium?

A

What was used to develop the impression and what is the signurature of that medium.

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15
Q

What is development medium?

A

It is used to render a fingerprint impression visible or to increase the contrast between the friciton ridge detail and the substrate.

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16
Q

What is considered when analysing deposition pressure?

A

Refers to the amount of downward pressure that is exerted on the firction ridges when in contact with the substrate.

Heave - Moderate - Light

17
Q

What is considered when analysing lateral pressure/distortion?

A

Refers to the movement of the finger after contact is made with the substrate (or pressure distortion). The most common form of distortion and flexibility of FR lends to distortion.

May occur:

  • on initial contact
  • contact is maintained
  • contact is broken
18
Q

What is considered when analysing clarity?

A

The two functions of clarity are that it:

  1. dictates the level of details available for comparision.
  2. Dictates the level of Tolerance for discrepencies.

Comparision cannot be done with level 1 details only.

19
Q

What are the levels of clarity?

A

Level 1 - friction ridges visible. Overall pattern.

Level 2 - the specific friction ridge paths, including major ridge path deviations.

Level 3 - the intrinsic shapes that are present within the friciton ridges such as:

relative pore location; alignment or misalignment of ridge units; ridge unit shape.

20
Q

What is tolerance?

A

If the quality of the impession is GOOD, the tolerance level for discrepencies is LOW. A LESSER area of friction ridge detail is required to eliminate or individualize.

If the quality of the imprression is POOR, the tolerance level for discrepencies is HIGH. A LARGER area of friction rdige detail is required to eliminate or individualize.

BASIS OF QUANITATIVE-QUALITATIVE ANALYSIS

21
Q

What is considered during comparision of FR impressions?

A

Always compare from unknown to known. Done to minimize preconcieved notions and remain objective (reduce bias).

2 stage approach:

  1. What class characteristics are present to narrow down seach (digit determination, pattern, relative core/delta distance, major ridge path deviations).
  2. Comparing level 2 and level 3 details.
22
Q

What is considered during the Evaluation step of the ACE-V methodology?

A

Two questions must be answered:

Is there agreement of friction ridge detail between the questioned impression (unknown) and the known?

Is there sufficient uniqueness in the friciton ridge detail to individualize?

23
Q

What factors allow you to make a subjective decision and be confident in your answer?

A

knowledge, training, experience

24
Q

What are the three possible findings of the FR identification process?

A
  1. Exclusion - donors are not the same
  2. Individualization - donors are he same
  3. Inconclusive - cannot individualize or eliminate
25
Q

What is the verification stage of the ACE-V methodology?

A
  • forms part of the methodology
  • part of the peer review process
  • two levels in the FR identification
    • verification of the methodology (theory) and the identificaiton process (technique) to ascertain if they are sound (scientific review)
    • verification of this case
26
Q

What biases need to be avoided during the ACE-V process?

A

Cognitive Bias - effect of perceptual or mental processes on the reliability & validity of one’s observations and conclusions (fatique, impariment, etc).

Contextual Bias - effect of information or outside influences om the evaluation and interpretation of data.

Confirmation Bias - tendency to search for data or interpret information in a manner that supports one’s preconceptions (fit evidence to theory).

27
Q

What are the indicators that a fingerprint impression was left by a thumb?

A

Thumbs can often be recognized by the following:

  1. The Shape
  2. Core area is lower in the fingerprint
  3. Often a side impression
  4. Found alone
  5. Position of the fingerprint
  6. Tip ridges slope in an ulnar direction
  7. Lack of phalange
28
Q

What are the characteristics of Top/Distal Transverse Crease?

A
  • Starts below the little finger on the hypothenar edge of the palm
  • Travels across the palm (transverse)
  • Ends near the index finger
  • MAY exit the hand or stop in the area between the index and middle fingers
  • Often characterized by “Crow’s feet” on the hypothenar edge of the palm
  • Flow of the foot opens up and down toward the edge of the hand
  • Ridges above the hypothenar edge of the crease arch up
  • Ridges below the hypothenar edge of the crease remain flat
29
Q

What are the charateristics of middle/proximal tranverse creases?

A
  • Originates on the thenar side of the hand, between the thumb and index finger
  • Tends to flow toward the center of the palm
  • Usually ends somewhere in the hypothenar area
  • Shortest of the major crease
30
Q

What are the characteristics of the bottom/thenar crease?

A
  • Begins on the thenar side in the same area as the middle crease
  • Usually converges with the middle crease and may even cross over it before reaching the thenar edge of the palm
  • Travels from starting point, in a semi-circle around the thenar pad and exits at the bottom on the thumb side of the carpal delta
31
Q

What are White Line Creases?

A
  • influenced by shape and flexibility of hand
  • folds or buckling of skin surface
  • formed after friction ridge differentiation
  • no subcutaneous attachment
  • increase with age
  • may be altered over time
  • able to follow ridges across

Forensic Identification Course (19 decks)

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