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VPD Understudy > Board Prep > Flashcards

Board Prep Flashcards

1
Q

Define Fingerprint

A

Is the pattern of friction ridges, found on the palm side surfaces of fingers, or the impression made by same.

3 dimensional structures on a 2 dimensional surface (generally)

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2
Q

What are the 4 basic premises of personal identification using impressions

A

1- FR develop on the foetus in their definitive form before birth
2- FR are persistent throughout life except for permanent scarring
3- FR patterns and the details in small areas of FR are unique and never repeated
4- Overall FR patterns vary within limits, which allow for classification

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3
Q

What is a latent fingerprint?

A

Is a FP that is not visible without the use of a development method

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4
Q

What is level 1 detail?

A

There is the presence of FR and show an overall ridge pattern

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5
Q

What is level 2 detail?

A

Major ridge paths and ridge path deviations (ridge characteristics)

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6
Q

What is level 3 detail?

A

Specific shapes of the ridges and details within the characteristics, such as pores and ridge shapes

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7
Q

Define loop pattern

A

One or more ridges enter from one side, recurve and exit from the same side

Pattern has a core and one delta

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8
Q

Define an Arch pattern

A

Ridges enter from one side and exit from the opposite side

Forms a wave like pattern

No delta

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9
Q

Define a tented arch

A

Ridges enter from one side and exit from opposite side, except for an up thrusting ridge or ridges in the centre that tend to bisect ridges above

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10
Q

Define whorl

A

Generally a circular arrangement of ridges in the central pattern area

Pattern has a core and at least 2 deltas

Counter clockwise generally indicates right hand

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11
Q

What is a delta?

A

It is where 3 sets of ridges meet.

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12
Q

What is the core?

A

It is the central focal point, but not necessarily the centre of the print.

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13
Q

What are the major ridge characteristics that can be found on impression?

A 
Ridge endings
Bifurcations
Ridge dots
Short ridges 
Enclosures
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14
Q

What are the areas of the palm?

A

Thenar - by the thumb
Hypothenar
Interdigital

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15
Q

What are the three palm creases?

A

Distal transverse
Proximal transverse
Radial longitudinal

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16
Q

What are the types of impressions you can find?

A 
Latent 
Visible 
Take away
Moulded 
Deposit - most prints are this type
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17
Q

What is Locard’s exchange principle?

A

Every contact leaves a trace

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18
Q

When looking at a surface, what things may affect the likelihood of finding prints at a crime scene?

A

Size
Continuity
Material

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19
Q

What factors affect the choice of powder to use at a crime scene?

A

Colour and composition of substrate

Type of suspected matrix

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20
Q

What type of brushes do we use and what for powders

A

Zephyr fibreglass - granular powders
Camel hair brush - to clean a print with too much powder
Magnetic wand - used on magnetic powders

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21
Q

What are the characteristics of metallic powders?

A 
Lightest and most finely ground 
May become electrostatic 
Use sparingly
Best on hard, smooth non-porous surfaces
Avoid sticky surfaces
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22
Q

What are the characteristics of granular powders?

A

Tend to be abrasive

Gritty

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23
Q

What are the characteristics of magnetic powder?

A

Contains ferrous particles which carry the powder
Can be used on paper, cardboard, vinyl, plastics and leather
Do not use on ferrous metal surfaces - examples CD, computer equipment or other electronic equipment w/o owner permission (destructive)

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24
Q

What is the purpose of forensic photography?

A

To provide and accurate and unbiased visual record of a crime scene and/or evidence.

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25
What is light?
It is a form of electromagnetic radiant energy to which the naked eye is sensitive. It can radiate outwards from the energy source (sun, flash etc) or be reflected from the objects surrounding us
26
What are the basic components of the camera used?
The body - houses the other components The lens - an optical device that focuses light into the sensor The recording system - an electronic sensor and data storage device The light control system - aperture, shutter, sensor sensitivity and light meter The viewfinder - a way to aim the camera to capture desired subject
27
What are the 3 camera settings can be used to control the exposure?
ISO number - sensitivity to light Aperture - the opening in the lens Shutter speed - the length of time the shutter is open
28
What happens when you double the ISO value?
It doubles the sensor’s sensitivity to light. Trade off is the increased sensitivity means increased digital noise
29
What happens when you change the aperture (f-stop) to the next higher number (example f-8 to f-11)?
You half (decrease) the amount of light reaching the sensor. The bigger the number the smaller the lens opening
30
What happens when you change your f-stop to the next lowest number (eg f8 to f5.6)?
You double (increase) the amount of light that reaches the sensor. The smaller the number the larger the lens opening
31
What is depth of field?
It is the acceptable sharpness within a photo that appears to be in focus. (In front of and behind the subject) The best is 1/3 in front and 2/3 behind The smaller the aperture (higher #) the greater the depth of field (More of image in focus)
32
What happens when you increase the shutter speed? What happens when you decrease the shutter speed?
The exposure time decrease by half when you increase the shutter speed (ex: 1/250 to 1/500) The exposure time doubles when you decrease the shutter speed (ex: 1/250 to 1/125)
33
What does TTL metering refer to?
It is the “Through the lens” metering and measures the light that passes through the lens. The sensor is balanced at average ambient light reflectivity of 18% Be careful in very white/bright areas and dark/black areas and adjust compensation accordingly. (Bright add light dark take light)
34
What is meant by lossy images?
It is a compressed version of a digital image and is generally a jpeg format. It minimizes. The file size Each time it’s opened and saved in same format it is compressed again and more detail is lost.
35
What is meant by lossless images?
Non compressed file format for digital images such as TIFF or RAW file format. Makes for larger file formats. No data compression therefore no details lost
36
What does inverse square law mean?
The intensity of the light drops (diminishes) as the distance from the light source increases
37
What should all images be?
Sharp, with adequate depth of field Correctly exposed Relevant and meaningful
38
What was it that Dr Mayer the first to recognize and publish? (Became a premise)
The overall patterns and uniqueness of details in fingerprints. Remarked that the arrangements of ridges is never repeated
39
What was Herschel known for?
Recorded his own fingerprints over the years to show they don’t change over the years
40
What were the major findings of Harold Cummings research?
Volar pads regress during friction ridge development The shape, symmetry and elevation of pads affect ridge alignment Explained randomness
41
What is Wilder known for?
The patterns are determined by the location of the volar pads Talked about Differential Grown results in the uniqueness of fingerprints
42
What is Whipple known for?
Friction ridge patterns are a result of the external forces and the pressures for adjacent ridges Studied mammals - all 5 digit mammals had typical arrangement of volar pads
43
What is Hale known for?
Documented the stages of ridge development (studied fetuses) Described Differential Growth Confirmed persistency and uniqueness
44
What is Okajima known for?
The appearance of dermal papillae change for the overall size and placement stay the same (persistency) Also studied incipient ridges
45
Who is responsible for bringing fingerprints to Canada?
Edward Foster
46
When was the first conviction in Canada that was based on fingerprints
1914
47
What are the wave lengths that can be seen with the naked eye?
400-700 NM
48
What is light?
An electromagnetic radiant energy that is visible to the human eye
49
What is a forensic light source?
It is a device that emits electromagnetic radiant energy at specific wavelengths and at wavelengths such as IR and UV which are also used in forensics
50
How are Fluorescence used in forensics?
We use forensic light sources set at specific wavelengths to make chemicals fluoresce. Some of the wavelengths can be blocked out with a barrier filter.
51
What is Stokes Shift?
It is the difference between the peaks of the excitation filter and the emission wavelengths.
52
What does LASER stand for?
Light Amplification by Stimulated Emission of Radiation
53
What type of forensic light source do we use at VPD
Polylight PL500
54
What LASER do we use at VPD?
Coherent TracER. - set at 532 NM
55
What does WHIMIS stand for and what is it
Workplace Hazardous Materials Information System - provides the classifications of hazardous materials and provides labelling
56
What does MSDS stand for and what does it provide?
Material Safety Data Sheet - it is a document that provides information about the potential hazards associated to the product - health, fire, reactivity, how to safely handle/store
57
How does cyanoacrylate work?
Liquid is vaporized by heat (chamber) or reduced pressure (vacuum) The monomers bond and form polymers (polymerization) and bond to fingerprint matrix
58
what are the characteristics of Ardrox
Use a UV light to see (under 400 NM) Shows greenish-yellow Use clear glasses
59
What are the characteristics of Brilliant Yellow 40?
Ethanol carrier Use 450-485 NM Yellow in appearance Use orange googles and orange filter (to photograph)
60
What are the characteristics of Rhodamine 6G?
Can be mixed with either methanol or water Use 450-515 NM (505 NM usually best) Yellowish-green appearance Use orange googles and filter
61
What are the blood reagents that can be used?
Amido Black and Hungarian Red (work with the proteins) Leucomalachite Green, Leuco crystal violet, luminol and blue star
62
Which blood reagents can provide more detail?
Amido Black Hungarian Red Leucomalachite Green LCV
63
Which blood reagents are used for searching
Luminol | Blue star
64
What processes react with the amino acids in fingerprints?
Ninhydrin Thermanin Indanedione - with or without zinc chloride DFO Ninhydrin with zinc chloride (fluorescent)
65
What chemical process to use on a porous surface that has been wet?
Physical developer | Oil red O
66
What chemical process is used on a wet non-porous surface?
Moly-Di | Small Particle Reagent (SPR)
67
What chemical reagents should be used on dry porous surfaces?
``` Fluorescent powders Ninhydrin Thermanin Indanedione with or without zinc chloride DFO ```
68
What process should be used on the sticky side of tape?
``` Sticky side powders Titanium Dioxide (dark surface only) ```
69
What are the 2 functions of the barrier filter?
Blocks unwanted light | Allows the desired light to pass through
70
What does SICAR stand for?
Shoe Impression Capture and Recovery
71
What are the conclusions that can be made during a footwear comparison?
Insufficient detail to form an opinion Exclusion Inclusion Individualization
72
As an FIU member when do you take video?
RE-enactment Some warrants Serious crimes Crowds
73
What are the 3 primary patterns types when describing blood?
Gravity patterns Spatter patterns Transfer patterns
74
What is the type of IR camera used in VPD?
Modified Nikon D750 with an IR filter on the sensor
75
What size aperture should you use when using the IR camera?
Use a smaller aperture to maximize the depth of field
76
What flash is used with the IR camera?
Nikon SB900 with 715NM filter
77
What is the relationship between Aperture and depth of field
A wider the aperture (small number) the shallower the depth of field A smaller aperture (large number) the more the depth of field
78
Who is the current President of the Canadian Identification Society? And the BC Representative?
President - Tamryn Loy Son BC Representative - David Stengert
79
What does DSLR stand for?
Digital Single Lens Reflex
80
What type of camera is used in the VPD?
Nikon D750
81
What are the types of fingerprint impressions found?
``` Take away Visible Deposit Molded Latent ```
82
What are the methods you can use to preserve an impression?
Photographs Lifts Cast
83
What are the 3 types of bias you can have?
Contextual bias Confirmation bias Cognitive
84
What is the flash that we use at VPD?
Nikon SB5000
85
what are the characteristics of the dermis?
It is the inner layer of skin that feeds the epidermis It is a matrix of connective tissues Protects the underlying structures (organs and tissues)
86
What does the direction of the print leaning tell you about what hand it may be?
Fingerprints tend to lean, at the top, towards the thumb of the hand the digit comes from
87
What is skin?
A soft outer covering on vertebrates It is an organ (a collection of tissues with a function)
88
What are the 3 random events of ridge development?
Random timing of events Random growth pressures Random growth processes
89
What are the stages of ridge development according to Hale?
Initial stage - primary ridges multiply and branch. Sweat glads develop Secondary stage - primary ridges stop growing and secondary ridges develop Result - dermal papaille develop around the sweat glands
90
What is ridgeology?
The study of the uniqueness of friction skin and its use for personal identification Coined by Ashbaugh.
91
What is luminescence?
Emission of light, not involving heat
92
Who came up with poroscopy?
Dr Edmond Locard
93
What is individualization?
Establishing that 2 impressions have come from the same digit
94
What is the importance about papillary pegs
It forms in double rows with pegs Strengthens the bond between dermis and epidermis Shows as double peg rows if the epidermis is sloughed off
95
How are sweat pores unique?
Size Shape Location
96
What are the underlying skin structures of friction skin
Primary epidermal ridges (directly under the friction ridges and contain pore structures) Secondary epidermal ridges (directly under the furrows) Dermis Papillary pegs
97
what is Dr Faulds known for?
First to use prints in court Proposed Scotland Yard adopt fingerprints to ID criminals

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