1
Q
Layers of the epidermis
A
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
2
Q
Layers of the skin
A
Epidermis
Dermis
Hypodermis
3
Q
Persistency
A
Basal cell communication
Structural elements:
- desmosomes
- basement membrane
- dermal papillae
- sweat glands
4
Q
Volar skin
A
-Found on soles of feet and palms of hands
- less pigment
- no sebaceous glands
- sweat glands
- friction ridges
5
Q
Smooth skin
A
-hair
-sebaceous oil glands
- sweat glands
- no friction ridges
6
Q
Primary ridges
A
Located underneath friction ridges on underside of epidermis
7
Q
Secondary ridges
A
Located underneath furrows on underside of epidermis
8
Q
Basement Membrane Zone
A
Anchors the epidermis and dermis together
9
Q
Dermal papillae
A
Peg like formations on the surface of the dermis located next to primary ridges.
Run in two rows
10
Q
Whose extensive research of fetal skin cross sections showed development of dermal papillae?
A
Alfred Hale
11
Q
Whose research showed the dermal papillae are in two rows on the dermis hugging the primary ridges located on the underside of the epidermis and break down as we age?
A
Michio Okajima
12
Q
Scars
A
Permanent damage to the basal layer or beyond through injury or disease.
13
Q
Friction skin persistency
A
- Basal cell mitosis: cell communication and replication
- Structural elements:
1. desmosomes,
2. basement membrane,
3. dermal papillae
4. sweat glands
14
Q
Who described evolution of friction ridges in mammals?
A
Inez Whipple
15
Q
Whose extensive research showed Volar pad regression occurs concurrently with primary ridge formation?
A
Harold Cummins
16
Q
Whose study of thin cross slices of fetal skin determined timing and development of primary and secondary ridges?
A
Alfred Hale
17
Q
Patterns develop due to
A
Volar pad: size shape and symmetry
18
Q
Who first suggested these centres of disturbance of friction ridge formations represent the location of Volar pads?
A
Harris Hawthorne Wilder
19
Q
Core to Delta distances
A
Early ridge development with Higher Volar pads = high ridge count.
Later ridge development during Volar regression = low ridge count
20
Q
Whose extensive research on friction ridge skin showed size shape and location of Volar pads affect the overall print pattern?
A
Harold Cummins
21
Q
Who is credited with being the first to recognize that although friction ridge arrangements may be similar they are never duplicated?
A
JCA Mayer
22
Q
Who studied incipient ridges and determined they were primary ridges that did not fully develop?
A
Michio Okajima
23
Q
Highly discriminating features (uniqueness)
A
Random timing, random growth, and random pressures
24
Q
Who observed ridge patterns are affected by external forces and pressure from neighbouring ridges?
A
Inez Whipple
25
What are the two propositions an examiner needs to consider for a friction ridge analysis
Proposition 1 - The impressions were made by the same source
Proposition 2 - The impressions were made by different sources
26
What is a fingerprint
An impression made by the friction ridges of a finger
27
Unknown fingerprint
An impression of friction ridge detail from a finger where the source of the impression is unknown
28
Latent print
Impression of friction ridge detail not readily visible.
29
Questioned impression
An impression (known or unknown) used for comparison to an exemplar impression
30
Exemplar impression
Impression (known or unknown) to which a questioned impression is compared
31
Known fingerprint
Impression of friction ridges left from a finger under controlled conditions and the source of the impression is known
32
Minutiae
Events along a friction ridge path - features
33
Features of friction ridges
All details present in a fingermark or reference fingerprint including all levels of detail
34
Levels of detail
Level 1 - General flow of ridges (may or may not include pattern type)
Level 2 - specific pathway of a ridge in relation to other ridges as well as the major path deviations
Level 3 - individual ridgeology and pore location
35
The premises of quantitative/qualitative friction ridge analysis
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. The specific friction 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
36
Types of fingerprints
Latent
Visible
Moulded
Take-away
37
Suitability assessment
Quantity of features
Clarity of detail
Pattern type
Core/Delta
Distortions
38
7 factors of the Analysis phase
- anatomical factors
- substrate
- matrix
- development medium
- deposition pressure
- lateral distortion
- clarity/tolerance
39
Deposition pressure
- light - thin ridges/wide furrows
- moderate - ridges/furrows equal width
- heavy - wide ridges/narrow furrows
40
Distortion analysis
Minutiae can be displaced by 3 mm and orientation by as much as 30 degrees
41
Double touch
Two separate touches
42
Double tap
Double impression - portion of the finger was still on the substrate.
43
Clarity
- Dictates the level of detail available for comparison
- Dictates the level of Tolerance for differences
44
Tolerance
High clarity = low tolerance
Low tolerance = high clarity
45
Quantitative/Qualitative comparisons
Quality is good, tolerance for discrepancies are low. Lesser amount of friction ridge detail is required to eliminate or identify.
Quality of impression poor, tolerance for discrepancies are high. Larger amount of friction ridge detail is required to eliminate or identify.
46
Pattern force
Features are more frequent in a fingerprint due to pattern type and development of friction ridges.
47
At evaluation - 2 questions an examiner must ask
Is there agreement or disagreement?
Is there sufficient quality and quantity of agreement or disagreement to either identify or exclude.
48
Can incipient ridges be used for comparisons?
Yes
49
Purpose of Analysis in Ace-V?
- is the impression suitable
- gathering information phase
- all elements of the impression are analyzed objectively
50
Premises of friction ridge identification?
1. Persistent except for scarring
2. Develop and set before birth
3. Level 2 and 3 details are unique
4. Limits in development result in patterns that have been classified
51
Why do we compare unknown to known?
- an objective comparison
- discourages bias
52
When quality of detail in prints are good…
A smaller quantity of features is required to make an identification
53
When quality of a fingerprint is low…
A larger quantity of features is required to make an ident.
54
When quality of a fingerprint is low, tolerance is…
Higher for discrepancies.
55
When quality of a fingerprint is high, tolerance is…
Lower for discrepancies
56
Where are cells generated?
Stratum Basale
57
Where are cells sloughed off after mitosis?
Stratum Corneum
58
Deposition pressure
Ratio between ridge with and furrow width.
59
Why is friction ridge skin unique?
Random timing, growth, and pressures.
60
Where are short ridges often found
In the delta.
61
Four step process comparison:
- target area
- pattern
- anchor point
- ridge to ridge
62
3 types of impressions
- latent
- visible
- moulded
63
Purpose of powders
- make a latent impression visible
- contrast the background
- photograph
- be able to lift it
64
Types of powders
- regular
-fluorescent
-magnetic
65
Black powder used
Porcelain, China, painted wood, metal, glossy paper, freshly touched cardboard
66
Lightning grey powder use
Dark surfaces, clear clean glass, silverware, chrome
67
Chemist grey
Polished furniture, mirrors, windows/glass, black hard plastic
68
Sciluminate uses
Porous or non porous items - metal casings, leather, plastic shotgun shells, guns
69
Fluorescent powder uses
Use when it’s desirable to eliminate background interference.
- multicoloured surfaces, glossy magazine covers, photographs
70
Magnetic powder uses
Wood, paper, leather, other porous surfaces.
- for recently handled items 12-24 hrs
71
Markings for lifting a print
Date
File
R#
Initials
Scale
Orientation
72
4 steps for comparison
- target area
- pattern
- anchor point
- ridge to ridge
73
raster vs vector
raster - pixel based
vector - made of paths/curves dictated by mathematic formulas
74
pixel is an acronym for
picture element
75
pixel properties
size, location, colour value
76
sensor
light sensitive photodiodes records the luminosity values of light
77
colour interpolation
value based on surrounding pixels - represents the colour value of a digital image
78
bayer pattern
coloured filter on the light sensor
79
dynamic range
highlights, midtones, shadows
80
resolution
measurement of pixels in dimensions of height/width
PPI - pixels per inch
81
resizing
number of pixels not changed but will affect PPI
82
resampling
number of pixels changed - adds/deletes pixels to the photo
83
enhancing an image of impression evidence is to improve this
contrast
84
Inverse Square Law
intensity of light reaching an object
85
Lens
gathers light rays and brings them into focus on the sensor
86
Focal length
distance between lens and sensor
87
Normal lens
Approx. 50mm Lens - depicts the view of the human eye
88
If shutter speed isn't fast enough in Aperture Priority
- adjust aperture
- add flash
- use tripod
- adjust ISO
89
Perspective can be changed
through focal length and location
90
Confirmation Bias
- knowing the conclusion of another qualified examiner
- taking information from the known to "fit" the unknown
91
Contextual Bias
- suspect in custody/confession
- suspect's criminal history
92
Hiel Dror
Known for studying bias in forensic science
93
Two questions to answer for "Identification"
- sufficient details to say you can identify
- agreement of details between known/unknown impressions
94
Strategies to reduce bias
- limit exposure to contextual information
- analyze the unknown first and document the analysis
- GYRO
- Consult
- Mark features in agreement
- Blind verification
95
1997 Erroneous Identification to Shirley MCKIE
2011 Inquiry Recommendations
- fingerprint evidence is opinion evidence
- no longer use the term "100% certain"
- notes at comparison stage of any characteristics found
- features are demonstratable to anyone with normal eyesight
96
2004 Mayfield - Madrid Bombing
OIG Report
- documentation requirements
NAS Report
- Need research on accuracy, reliability, and validity
- Research on bias and sources of human error
- Integrated Team approach to develop standards
97
Errors in Mckie and Mayfield
Both were complex prints and involved human error
98
Expert/Novice Study by Tangen, Thompson, and McCarthy
Approx. 55% novice error rate
99
FBI Black Box Study
0.17% error rate
100
Miami Dade Box Study
Although initially stated error rates were quite high - the study was never published.
Error rate actually determined to be 0.19%
101
PCAST Report 2016
Foundational Validity - need for empirical studies, reproduce results, and measured
Validity Applied - reliably applied in practice and with proficiency testing
Alleged 1 in 18 identifications were false positives based on Miami Dade Box Study.
OSAC response - used an incomplete methodology and a calculation error
102
Statistical Models
Neumann - Number of minutiae in agreement increases the less likely it would be to find a similar arrangement of features in another source on average
103
Required elements for photographs to be admissible in court
- accurate representation of the scene
- proper perspective
- relevant
- unbiased -
104
What is crime scene photography used for
- investigative perspective - aid the investigator
- court perspective - understand scene/accurate representations of facts
105
Linkage
Using common objects present to link photographs as though walking through
106
Three types of evidence
Testimonial
Documentary
Physical
107
Locard's Exchange Principle
Cross transfer of physical evidence when two things come in contact with each other
108
Good sources of DNA
- blood
- saliva
-hair root
- tooth pulp
- bone marrow
- skin cells/muscle
- semen
- nasal secretions
109
Four responsibilities of FIS regarding evidence
- identify each piece of evidence
- describe where it was located
- prove continuity
- describe changes
110
Path of Evidence
- path taken by offender/victim
- most likely area to locate evidence
- outside to inside
- protect until examined
111
Safe Path
- path searched and cleared to allow access to personnel
112
Night Flash Techniques
- synchronized flash at camera
- slow sync
- rear sync
- multiple flashes at camera
- multiple flashes away from camera -
113
Night photography without flash
- available light
- painting with light
114
Studio lighting
- flash
- continuous lighting
115
Studio Flash Techniques
- Feathered
- Bounce
116
Reducing Shadows in the studio
- black background
- raise object off the surface
- light table
- light diffusion
117
Fingerprint Photography
- overall
- midrange
- close up - fingerprint, scale, circle, all markings
- As Close As Possible - fingerprint, part of scale, R#
118
R vs Mohan
- necessitate the trier of fact
- person is a qualified expert
- absence of any exclusionary rule
- relevance
119
R vs Abbey
court is the gate keeper of who is qualified to give expert testimony
120
What kind of evidence can an expert provide
Opinion
121
Cartridge
- Projectile
- Casing
- Powder
- Primer
- Centre or Rim Fire
122
Bullet Trajectory
Can help determine where to look for evidence: shooter standing and intended victim was
123
Cratering Effect of glass
Glass is blown away on the opposite side of where the force was applied
124
Radial Lines
Radiate from the point of impact on glass
125
Concentric Lines
Spider web between radial lines of impact on glass
126
Automobile paint is unique
- scrape to the metal
- send control from same panel as the damage
127
Gunshot Residue (GSR)
- propellent powder and primer (primer is the important one to test for)
- GSR found on backs of hands and face
- Transfer from gun to skin occurs when casing is discarded
128
Information footwear evidence can provide
- point of entry/exit
- path of evidence
- number of people on scene at time
- where they were standing
- link between crime scenes
- manner of track creation
129
2D footwear types
- transfer impression (positive) - wet or dry origin
- take-away impression (negative) - removing material from substrate
130
Non-destructive Searching Methods Footwear Impressions
- grazed lighting - parallel to surface
- oblique lighting - flashlight just off the surface
- electrostatic dust lifter - best on dry origin impressions
131
Destructive Searching Methods Footwear Impressions
Powders - good for wet-origin impressions on hard surfaces
Chemicals
132
Lifting Footwear Impressions
- ESDL - electrostatic dust lifter - dry impressions
- Gel Lifter - Wet or dry origin impressions
- Mikrosil - wet origin impressions
- Dental Stone - wet impressions or impressions on wood/concrete
133
Three main areas of the palm
- thenar
- hypothenar
- interdigital
134
Indication of twisting motion of a fingerprint
C-Shape
135
Three Major Creases
top
middle
bottom
136
Crime Scene Video
- date and time
- location
- file #
- person recording the video
- others present -
137
White Light
Visible light spectrum - wavelengths of 400 nm to 700 nm
138
Fluorescence
Light that is absorbed then re-emitted at a longer wavelength that can be visualized
139
Ultraviolet
Electromagnetic radiation with a wavelength shorter than visible light, but longer than an x-ray
140
Why use fluorescence
- enhance friction ridge detail
- eliminate backgrounds
- render latent impressions visible
- increase contrast of the impression and its background
141
Exciter Filter
Blocks unwanted wavelengths resulting in a coloured beam
142
Barrier Filter
- in front of the lens/eye
- blocks/absorbs unwanted wavelengths
- allows desired fluorescent wavelengths reflected from surface to pass through
- filter is chosen based on wavelengths
143
Ultraviolet Light Application
- search for hair, fibres, bodily fluid
- use with fluorescent powders
- use with dye stain
- reveal bruises
- enhance details of bitemarks
- reveal untreated fingerprints on textured surfaces
- analysis of inks
- counterfeiting detection
144
LASER
Light
Amplification by
Stimulated
Emission of
Radiation
145
Laser safety goggles must have what Optical Density
Optical Density of OD4
146
Most useful light to trigger fluorescence/use on crime scene
Blue light - 450 nanometres with an orange filter
147
Footwear ACAP focal length
35-60 mm lens
148
450nm with orange filter use on crime scene for
- search for hair, fibres, bodily fluids
- bones/teeth
- blood stains
- untreated prints on textured surfaces
- footwear impressions
- drugs/paint/grease
149
Three main dye stains in Forensic Examination
- Ardrox with UV Light
- Brilliant Yellow with 450nm light and orange filter
- Rhodamine 6G with 500-565nm light and orange or red filter
150
Cyanoacrylate
Fumes react with invisible fingerprint residues to form a visible white polymer
151
Techniques used to remove tape from surfaces
- Un-du
- Compressed Air
152
Fingerprint technique most used on dry porous surfaces
Indandione Zinc Chloride
153
Deciding on Chemical Techniques
- history of the exhibit
- seriousness of the offence
- practicality
- value of the item
- damage to the item
- substrate
- matrix
- time elapsed between deposition and development of print
154
Reference manual used for development methods
Fingermark Visualization Manual
155
What does ninhydrin react with
Amino Acids
156
Why use chemicals
- eliminate backgrounds/better contrast
- enhance prints: usually better quality and improves chances of finding prints
157
Porous DRY Sequence of Chemical Process
Indandione Zinc Chloride
DFO
Ninhydrin
Physical Developer
VMD
158
Porous WET Sequence of Chemical Process
Physical Developer
VMD
Oil Red O
159
Non-porous DRY Sequence of Chemical Process
CA
Dye-stains on CA
VMD
160
Non-porous WET Sequence of Chemical Process
Molybdenum Disulfide
VMD
161
Semi-porous Sequence of Chemical Process
CA
Powder on CA
Indandione Zinc Chloride
DFO
Ninhydrin
VMD
162
When presenting a plan drawing in court what is important to bring?
Ruler - measure different areas that were not documented
163
Three things to include in a rough sketch
- compass direction
- date/time
- address
- reference points
- who drew the sketch
- who measured
164
Methods of Measurement
- Triangulation
- Baseline/Right Angle Off Set
165
What is important to have in a planned drawing?
Scale
166
PPE to be worn in a lab setting
Eye protection
Lab coat
Gloves
167
Before using chemicals what do we review
Safety Data Sheet
168
SDS includes what
- identification of product
- hazards
- first aid measures
- handling/storage
- exposure control/PPE
- Disposal considerations
- toxicology information
- ecological information
169
Workplace label contains what
- Chemical name
- Safe Handling Precautions -
- Reference to SDS
170
Major consideration to be taken into account when lifting footwear impression with ESDL or gel lift
- the impression is laterally reversed
171
Why is it important to know how footwear is manufactured
- credibility in court
- can be used to exclude
- Class Characteristics are not overvalued as unique
172
Three types of footwear manufacturing
- injection
- compression
- open pour
173
Analysis for both unknown and known
- Class Characteristics
- Wear
- RACs
174
Class Characteristics of Footwear
Intentional and unavoidable - made during manufacturing and is not unique
175
RACs
Anything that happens outside of the manufacturing process
176
Shallamack Abrasion
Occurs on soft rubber - wear that looks like texture
177
Considerations of Class Characteristics
Size
Shape
Tread Pattern
178
Considerations of RACs
Size
Shape
Orientation
Location
179
Evaluation Considerations of Footwear
- similarities and dis-similarities between class, wear, and RACs
- are they explainable
180
5 opinions of Footwear and Tires
- Identification
- Exclusion
- Inconclusive
- Association of Class Characteristics -
- Higher Degree of Association -
181
Tire Components
Wear bar indicators
grooves
rib/rib elements
sipes
182
Approximate range new tires wear off whiskers from manufacturing process
5,000km
183
Reading Tire Size
P225/65 R17
P225 - Section Width
65 - Aspect Ratio (sidewall percentage)
R17 - rim diametre
184
Noise Treatment on tires
Varied arrangement of different pitch lengths of tread elements around the circumference of a tire
185
Types of tire molds
Segmented mold
Clamshell mold
186
Mold vent holes
Whiskers develop on tire surface - class characteristic
187
Tire track evidence measurements
- wheelbase
- front track width
- rear track width -
188
Record from Tire sidewalls
Tire brand/model
Tire Size
DOT number (last 4 digits of 12 digit number = week/year manufactured)
189
Legal Authority
Basic Search Warrant
General Search Warrant
Impression Warrant
190
Holdback evidence
Believed to only be known by suspects and police
191
FIS at autopsy
Photograph as per pathologist request
obtain fingerprints of deceased
192
Fingerprinting a deceased because...
ID prints at scene to victim
ID the victim
Conclude an FPS file
193
Subject Matter Experts
- bloodstain pattern analyst
- forensic entymologist
- forensic anthropologist -
- forensic archaeologist -
- forensic pathologist
194
Processing the suspect
- photograph suspect before seizing/swabbing
- photograph with scale
- examine hands, face, exposed skin for injuries
- swab bloodstains
- Powder residue - GSR kit
195
Non destructive search technique for blood
Reflected infrared - 700nm to 1000nm
196
Bloodstain Pattern Categories
- Gravity
- Transfer
- Spatter
197
Bloodstain Pattern Analysis
- size
- shape
- location
- distribution -
198
Bloodstain Patterns are both
Predictable and Reproducible
199
Direction blood was traveling can be determined by what
shape - its tail
200
Photography of bloodstains
- overall, midrange, close-up all with scales
- Take photographs perpendicular to the surface - with tripod
201
Blood reagents for enhancement
- Amido Black - reacts with proteins in the blood - used on porous and non-porous
- Aqueous Leuco Crystal Violet - reacts with heme in blood - used on porous and non-porous
- Hungarian Red (fluorescence) - reacts to proteins in blood - used on non-porous
202
Blood reagents for search
- luminol
- blue star
203
Physical Evidence Comparison Principles
- uniqueness - no two things happen in the exact same way
- identification - if proper methodology is followed and with sufficient clarity an object may be identified as originating from a particular source
204
Four possible opinions for Physical Evidence Comparisons
- inconclusive
- exclusion
- similar to
- identification
205
Three factors in fingerprint photography
- proper exposure and illumination
- sharp focus (depth of field)
- fill the frame (max resolution)
206
What is ridgeology
The study of uniqueness of friction skin and its use for personal identification - David Ashbaugh
207
What is forensic science
The application of scientific principles and techniques to matters of criminal justice especially relating to the collection, examination, and analysis of physical evidence.
