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Trace Evidence > Fingerprints > Flashcards

Fingerprints Flashcards

1
Q

What are fingerprints?

A

Tiny ridges, whorls and patterns on the tip of each finger

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2
Q

What are the 4 types of fingerprints?

A
  1. Central pocket loop
  2. Double loop
  3. Accidental loop
  4. Plain
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3
Q

Features of fingerprints

A
  1. Loops
  2. Whorls
  3. Arches
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4
Q

1st Level Detail

A
  • Pattern of ridges - loop, whorl, arch
  • Not sufficient for individualisation but can exclude
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5
Q

2nd Level Detail

A
  • Ridge characteristic - bifurcation, ending
  • Scars, creases and subsidiary ridges
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6
Q

3rd Level Detail

A
  • Individual ridge unit
  • Pore sizes, shape, relative position
  • Poroscopy
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7
Q

Define finger-mark

A

an unknown traces thats been left by a person on an object - the mark has a lesser quality impression which inc latent, partial, distorted etc

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8
Q

Define fingerprint

A

A print taken for identification

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9
Q

Types of Finger-mark

A
  • Latent
  • Plastic
  • Visible (either postive or negative)
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10
Q

Latent finger-mark

A
  • major source of fingermark evidence
  • deposited by individual when its directly interact with a surface/object
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11
Q

Three types of gland found on the skin: Latent fingermark residue

A
  • Eccrine: all over the body, highest density on palms and soles (predominant component)
  • Sebaceous: localised to regions inc hair follicle and the face + scalp (touching other parts of the body)
  • Apocrine: found in the axillary regions (armpit + groin) least contributon
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12
Q

Latent fingermark composition

A

The chemical composition of the mark found at a crime scene depends on

  • Original mark
  • Surface
  • Age/ time since deposition
  • Storage condition e.g. temp, light, water exposure etc
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13
Q

Forensic Evidence recovery (Initial assessment)

A

Type of item/surface
Condition of item/surface
History of item/surface
Presence of other forensic evidence type

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14
Q

Forensic Evidence recovery (Outcome of initial assessment)

A
  • Suitable for forensic evidence?
  • Suitable for fingermark recovery only?
  • Suitable for “ “ and other forensic evidence
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15
Q

Forensic Evidence recovery (Forensic evidence recovery strategy/plan)

A
  • Constraints and limitation
  • Force policies and or priorities
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16
Q

Purpose of visualisation and enhancement

A
  • Enhance of the ridge detail, minutiae
  • To provide contrast between the ridges and the background
  • Improve the chance of making an identification
17
Q

How can it be achieve? (visualisation and enhancement)

A
  • Visual examination (lighting)
  • Chemical enhancement tech
    those which react with components e.g ninhydrin
  • Physical enhancement
    those which detect the greasy nature of the surface e.g powder
  • Digital enhancement
18
Q

Visual examination

A
  • Visible lighting (inc diffuse, oblique, ring light)
    e.g all types of fingermarks
  • Fluorescence examination e.g latent fingermarks (sweat, oil, grease, contaminated finger-marks on a fluorescent surface, enhance finger-marks)
  • Specialist lighting e.g infrared reflection (metallic/inorganic deposition process) , ultraviolet reflection, multi spectral imaging
19
Q

Advantages and Disadvantages of visual examination

A

A: Non destructive, can be low tech, can be easy to carry out

D- Depends on the fingermark, can be high tech, difficult to carry out and record image

Must be carried out before, during and after treatments

20
Q

Chemical/Physical enhancement

A

Sebaceous material

Eccrine material

21
Q

How to treat exhibits?

A
  • Chemical and physical characteristic of a mark generally not known
  • Resulting mark arises from interaction between the mark, the substrate and environment: difficult to predict an individual case
  • Difficult to determine the age of a mark; many variable to take into account
22
Q

Triangle of interaction

A

Finger-mark composition
- Natural, eccrine-rich, sebaceous-rich, a contaminant present e.g blood, grease

Surface
- Texture, elasticity, rigidity, size, shape, condition, type of surface, material of surface

Environment
- Temp, humidity, exposed to water/other chem

23
Q

Fingermark enhancement

A

A process of forming a new image quality using various techniques + methods to obtain images that are more easily interpreted by the human eye

Trace Evidence (2 decks)

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