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CSI (3rd year) > fingerprints and exhibits > Flashcards

fingerprints and exhibits Flashcards

1
Q

what is the definition of a fingerprint

A

an impression of the friction ridges of all or any part of the finger

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2
Q

what does SWGFAST stand for

A

scientific working group on friction ridge analysis, study and technology

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3
Q

what are the elements of fingerprint theory

A
  1. human friction ridge skin is unique
  2. human friction ridge skin is persistent throughout the individuals lifetime
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4
Q

what is palmar human friction ridge skin

A

bottom of hands

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5
Q

what is plantar human friction ridge skin

A

bottom of feet

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6
Q

do the seuqences of the ridges/ arrangement of minutiae change during a person’s lifetime

A
  • no
  • except for injury
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7
Q

when are fingerprints fully formed

A

by the time a fetus is 6 months old

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8
Q

rank the following based on how much genetic similarity they share in their fingerprints unrelated persons of the same race, identical twins, parent and child, siblings

A
  1. most identical twins
  2. siblings
  3. parents
  4. least unrelated persons of the same race
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9
Q

how much square area does the skin take up

A

about 1.5 to 2 sq. metres

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10
Q

how much square area does friction skin take up

A

about 0.08 sq. metres

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11
Q

how thick is skin

A
  • most parrts of the body no more than 2 mm
  • heels 4mm
  • eyelids 0.5mm
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12
Q

what are the main functions of skin

A
  1. acts as a container for the skeletal structure and internal organs
  2. provides sensory input about external conditions
  3. provides a means for the elimination of waste products via sweating/ crying
  4. allows for the ability to grasp and grip objects
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13
Q

what are the main layers of skin

A
  • epidermis top layer
  • dermis bottom layer
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14
Q

what part of the skin is where the generating layer where new cells are formed

A

the bottom layer of the epidermis, next to the dermis

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15
Q

what are some characteristics of the epidermis

A
  • outer layer of the skin
  • protective barrier for the underlying tissues
  • must constantly replace cells leaving the surface
  • consists of 5 diff layers
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16
Q

what is this

A

a pore

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17
Q

what is this

A

a ridge

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18
Q

what is this

A

a furrow

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19
Q

what is this

A

a ridge ending

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20
Q

describe the dermis

A
  • the inner or bottom layer of skin
  • thick layer of fibrous and elestic tissue that gives the skin its flexibility and strength
  • contains nerves, sweat gland, and blood vessels
  • a layer of connective tissue that supports the epidermis
  • part of the sensory reception and temp regulation process
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21
Q

describe the composition of fingerprint secretions

A
  • almost 99% water
  • other 1% is oragnic/ inorganic salts, AA, and fats
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22
Q

what is the chemical composition of fingerprint residues

A

changes w time

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23
Q

why are diff techniques needed to visualize fingerprints

A
  • as water evaporates, the print dries out
  • also diff surfaces
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24
Q

what are the three levels of detail

A
  1. pattern
  2. ridge characteristics
  3. pores, ridge edges
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25
Q

what are the different fingerprint patterns (level 1)

A
  • loop lines enter on one side, recurve, and leave on the same side
  • whorl at least 1 ridge does a complete circle
  • arch lines enter on one side and leave on the other
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26
Q

how many ridge characteristics does the average finger contain

A

150

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27
Q

what are minutiae

A

characteristics of ridge patterns

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28
Q

what do we look at for level 3 detail of fingerprints

A
  • position of pores
  • edge shapes
  • creases
  • scars
  • incipident ridges
29
Q

can level 3 details be used to identify a fingerprint

A

not on their own

30
Q

what is an incipient ridge

A

an immature friction ridge, thinner than those surrounding it

31
Q

what are other names for incipient ridges

A

false, rudimentary, or nascent ridges

32
Q

can incipient ridges be used for classification purposes

A

no

33
Q

can incipient ridges be used for identification purposes

A

yes, if present in both crime scene and inked impressions (if its not there it doesnt mean they can be concluded as different)

34
Q

what is the acronym for the fingerprint comparison process

A
  • ACE-V
  • analysis
  • comparison
  • evaluation
  • verification
35
Q

what happens during the analysis step of the ACE-V method

A
  • the assessment of an unknown impression to determine suitability for comparison
  • pattern and ridge characteristics of unknown impression are observed and noted
  • if not suitable, then the examination process ends here
36
Q

what notes should be made in a notebook about the fingerprint

A
  • level 1 detail
  • level 2 detail
  • level 3 detail
  • substrate (suface)
  • matrix (residue composition
  • deposition pressure
  • development medium
  • anatomical aspects
  • clarity
37
Q

what are examiner’s bench notes

A
  • notes made in notebook
  • the final formal report is written based on these
  • all notes must be included in disclosure
38
Q

can you individualize and exclude fingerprints based on level 1 detail

A
  • cannot individualise
  • may exclude
39
Q

can you individualize and exclude fingerprints based on level 2 detail

A
  • can individualize
  • can exclude
40
Q

can you individualize and exclude fingerprints based on level 3 detail

A
  • cannot individualize
  • cannot exclude
  • not on their own, but can be used along w other details
41
Q

what are anatomical aspects

A

how the object was handled and the way the print was deposited

42
Q

what is a substrate

A

the type of surface on which the impression was located + how it impacts the appearance of the fingerprint

43
Q

what is a matrix

A
  • what material or medium was deposited on the substrate by the finger
  • (ex. sweat in combination of oil, dirt, blood, grease etc)
44
Q

what is deposition pressure

A

the amount of downward pressure exerted by the finger on contact w the substrate

45
Q

what is lateral/ pressure distortion

A

the assessment of movement of the finger while in contact w the substract

46
Q

what is clarity

A

the visual quality of hte friction ridge detail (clear or obscured)

47
Q

what happens during the comparison step of the ACE-V method

A
  • the comparison of 2 or more impressions to determine if theyre similar or not
  • examiner compares the unknown print side by side w the known print
  • done in an objective manner
48
Q

are comparisons made from the known to unknown, or unknown to known

A

unknown to known

49
Q

what happens during the evaluation step of the ACE-V method

A
  • an examiner assesses the value of the details observed during the analysis and comparison steps, reaching a conclusion
  • the conclusion is the opinion of the examiner and is subjective in nature
50
Q

what are the potential outcomes of a fingerprint evaluation

A
  • identification/ individualization from the same source
  • exclusion not from the same source
  • inconclusive unable to identify or exclude from being from the same source
51
Q

what does it mean if two fingerprints have exclusion

A

there is sufficient quallity and quantity of detail in disagreement to conclude that 2 areas did not originate from the same source

52
Q

what does it mean if two fingerprints have identification

A

there is sufficient quallity and quantity of detail in agreement to conclude that 2 areas did originate from the same source

53
Q

what does it mean if two fingerprints have inconclusive

A

there is neither sufficient agreement to individualize, nor sufficient disagreement to exclude

54
Q

what are key details revolving the identification decision

A
  • conclusion reached is the opinion of the edxaminer
  • this opinion is subjective
55
Q

what is the minimum number of features required to report an identification decision

A
  • no predetermined number
  • based purely on the quantity, quality, and rarity of features observed
  • relies on training, experience, and knowledge of the examiner
56
Q

what types of fingerprint impressions are there

A
  • latent not readily visible to the naked eye
  • visible readily visible without the use of development technique
  • moulded impressions that retain the 3D shape of the ridge detail
57
Q

what do you use to process a nonporous surface

A

powders or glue fuming

58
Q

what do you use to process a porous surface

A

chemical processes

59
Q

what is powdering

A

the application of finely ground, coloured powder to a nonporous object to make latent prints visible

60
Q

what brush type is used for powdering

A
  • fiberglass filament brush
  • camel-hair brush
  • feather duster
61
Q

can a print be over-powdered

A

yes

62
Q

how do you powder a fingerprint

A
  • apply a small amount of powder onto the surface and begin to brush
  • brush in the direction of any ridges that begin to appear
  • stop when latent print reaches point of sufficient clarity
63
Q

how do you mark a fingerprint

A
  • circle w wax pencil or dry erase marker
  • use letter R and number sequentially
  • date and your initials
  • place scale close to edge of print without touching print (after initial photos)
  • powder scale and circle
64
Q

how do you photograph a fingerprint

A
  • overall and midrange
  • closeup and closeup w scale
  • literally the same as every other photo
65
Q

how do you lift a fingerprint

A
  • use a hinge lifter or roll of tape
  • place the edge of the tape on the surface in front of the latent print
  • applying downward pressure, move along the piece of tape until it fully covers the print
  • pull back on the tape lifting the print and place on lift card
  • avoid creasing
66
Q

how long can exhibits be stored

A

anywhere from 1-100 years (depending on the case)

67
Q

what are the guidelines to follow for packing exhibits

A
  • should be acceptable by CFS
  • refer to CFS evidence handbook for direction
68
Q
A

CSI (3rd year) (9 decks)

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