STUDY MATERIAL AFTER MIDTERM Flashcards
(144 cards)
1
Q
What range in Nanometers is visible to the human eye?
A
400nm to 700nm is visible light to the human eye
2
Q
Fluorescence Definition
A
Fluorescence
* Fluorescence is the emission of light by a
substance which has absorbed light or other
electromagnetic radiation.
* In most cases, the emitted light has a longer
wavelength, and therefore lower energy, than
the absorbed light.
3
Q
Why Fluorescence?
A
Fluorescence allows us to:
- enhance friction ridge details
- eliminate backgrounds
- render latent impressions visible
- increase contrast between impression and background
We achieve fluorescence through the application of chemicals or powders and the use of filters.
4
Q
Two kinds of filters:
A
Exiter filter
Barrier filter
5
Q
Common light sources we use for excitation radiation:
A
- Ultraviolet (UV) light
- Forensic Light Source (FLS) – filtered lamps
AKA - Alternative Light Source (ALS) - LASER
6
Q
What PPE is required for Chemicals and Alternative Light sources/
A
Gloves, long sleeves and Eye Protection
7
Q
Why do we use Ultraviolet (UV) Light
A
- Search for hair, fibers, bodily fluids
- Use with fluorescent powders
- Use with dye stain – Ardrox
- Reveal bruises
- Enhance details of bite marks
- Reveal untreated fingerprints on
textured surfaces
Other applications:
* Analysis of inks on questioned
documents
* Counterfeiting detection of bank notes
8
Q
Goggles MUST have an Optical Density factor of OD___ at 532 nm
or better.
A
OD4
9
Q
The most useful light to trigger fluorescence at
crime scenes is blue at approx. _____nm
A
450
10
Q
What do we search for with Blue Light?
A
- Hair, fibres, bodily fluids
- Bones, Teeth
- Bloodstains
- Untreated fingerprints on textured surfaces
- Footwear impressions
- Drugs, Paint, Grease
11
Q
Some examples Powders and Chemicals we use for Non porous and porous surfaces?
A
- Non-porous surfaces
- Fluorescent powders
- Cyanoacrylate + dye stain
o Ardrox
o Brilliant Yellow
o Rhodamine 6G - Porous surfaces
- DFO (1,8 Diazafluoren-9-one)
- IND-Zn (1,2-indanedione zinc chloride)
12
Q
Why use chemicals?
A
- Eliminate background for better contrast
- Improve chances of finding impressions
- Quality of impressions developed with
chemicals is often better than when
developed with powders
13
Q
Process we do for non-porous
A
- Cyanoacrylate fuming
- Fluorescent dyes or fingerprint
powders - Vacuum Metal Deposition (VMD)
14
Q
CA stands for _____________________________
A
Cyanoacrylate
15
Q
Porous Chemical Sequence
A
1A In/Zn
or
1B DFO
2 Ninhydrin
3 VMD
4 Oil Red O
5 Physical Developer
16
Q
Wet Porous Chemical Sequence
A
1 VMD
2 Oil Red O
3 Physical Developer
17
Q
Non-Porous Chemical Sequence
A
1 CA
2 CA + Dye
3 VMD
18
Q
Wet Non-Porous Chemical Sequence
A
Molybdenum Disulphide/ Small particle Reagent
or
VMD
19
Q
Semi- Porous Chemical Sequence
A
1 CA
2 Florescent dyes or fingerprint powders
3 VMD
20
Q
Why do we use filters?
A
- to apply light of a specific wave length range for excitation radiation
- to see fluorescence
- to photograph fluorescence
21
Q
What does LASER stand for?
A
Light
Amplification by
Stimulated
Emission of
Radiation
22
Q
What are common problems when using chemicals that fluoresce?
A
- incorrect match of excitation light and chemical
- no barrier filter on camera
- incorrect barrier filter
- insufficient time for eyes to adapt
23
Q
What part of the matrix reacts to chemicals?
A
- eccrine sweat
- sebaceous oils
- lipids
- other contaminants
24
Q
When using chemicals at a scene what are factors to consider?
A
- history of the substrate: dry, wet, previously wet
- seriousness of the offense
- availability of chemicals/ powders
- value of item
- potential for damage
- substrate
- matrix
- time elapsed between deposition and examination
25
What should a WHIMIS label include?
- name of product
- pictogram
- signal word
- hazard statement
- precautionary statement
- supplemental label
- name of supplier
26
What is the best chemical process for processing thermal paper?
- VMD
- acetone and ethanol wash
27
What part of the matrix does the vmd target?
Fats
Amino acids
Eccrine sweat
28
What can blue light detect at the morgue?
- bodily fluids
- bloody latent marks
- bite marks and bruising
- unusual marks
29
What is the nm wave length of a laser?
A single wave length of 532nm
30
What can a laser be used for?
- search for hairs and fibers
- used as excitation radiation for fluorescence following a chemical application
31
Through what application do we achieve fluorescence?
- chemicals
- powders
- use of filters
32
At the start of your video you should start with
a sign on to provide the following information:
Date & Time
. Location
. File number
. Person recording the video
. Other persons present
33
When taking videos, how long should you wait at the beginning/end of the pan shot before stopping/moving?
5-10 sec
34
Name two reasons why you would use a dye stain on exhibits treated with CA (cyanoacrylate fuming).
The main two reasons for using dye stains are to enhance the impression and create greater contrast between the fingerprint and the background.
35
Match the following dye stains that are used with exhibits that have been treated with CA to their recommended viewing FLS wavelength.
505-535 nm
450-485 nm
UV
Ardrox
Brilliant Yellow
Rhodamine 6G
36
What does ninhydrin react with?
Amino Acids
37
What is the recommended examination process for wet glass?
Molybdenum disulphide also known as Moly-Di or Small partical reagent (SPR)
38
For general searching of a crime scene, what is the optimal wavelength of an alternate light source to use?
450nm
39
What is the recommended dye used to view friction ridge detail developed with CA using the laser?
Rhodamine 6G
40
T or F
A 360 degree pan should always be completed in one shot.
F
41
List three considerations when determining how to treat an exhibit with a chemical process.
There are a large number of considerations including: substrate, matrix, type of offence, value, sentimental value, and the portability of the object
42
A crime scene video should include overall, midrange and close-up shots of an item of interest. The best way to accomplish this is to:
Film the overall shot, pause and then get closer to the point of interest and re-establish the shot at a midrange and continue filming
43
Place the following processes in the correct order that should be used to develop a fingerprint on a piece of paper.
Ninhydrin
DFO/IN DN
Visual Exam
Oil Red O/ Physical Developer
VMD
Visual Examination - DFO or Indaindione Zinc Chloride, Ninhydrin, VMD, Oil Red O and Physical Developer
44
T or F
In fluorescence photography, the barrier filter is always placed in front of the light source.
F
45
Name two reasons why you would use a dye stain on exhibits treated with CA (cyanoacrylate fuming).
Enhance the impression and create greater contrast between the fingerprint and the background.
46
What to include in the rough sketch?
− Compass direction (North arrow)
− Date & Time sketch was made
− Precise address of the location
− Reference points used
− Who drew rough sketch
− Who took the measurements
− Other pertinent information
47
What to measure for Indoor scenes?
* Length and width of the rooms
* Thickness of walls
* Thickness and width of doors and direction of swing
* Furniture and anything that could be considered evidence
* Stairways
48
4 parts of the shoe bottom
Toe, forefoot, arch, heel
49
3 parts of shoe
Upper, outsole, midsole
50
Why are hand molds important?
Variations in outsoles made by hand molds
51
Why is texture important on the bottom of a shoe
It can indicate wear. Texture is valuable when comparing general wear.
52
2 types of molding
* Compression Molding
* Injection Molding
53
What is Compression molding?
Waffle maker
54
What is Siping in shoes or tires?
Thin cuts in outsole to improve traction (boat/deck
shoes). Small slits in undersole instead of 3d ridges
55
What are the 3 things in footwear that we analyze during the analysis phase?
* Class Characteristics (i.e., level 1 detail)
* General Wear
* Randomly Acquired Characteristics
56
Possible opinions for footwear comparison conclusion:
* Inconclusive
* Exclusion
* Association of class
characteristics
* Higher degree of
association
* Identification
57
Philosophy of Footwear Identification
“Footwear Identification is established by the
agreement of class and accidental
characteristics of such significance or number
that no other logical conclusion can be
reached.”
58
what 3 things do we look at during
Comparison of footwear?
* look for differences and similarities
* compare unknown to known
* compare like to like
* 2D Scene Impres
* 2D Scene Impressions to 2D test impressions
* 3D Scene impressions to 3D test impressions
59
How many test impression methods must be used for footwear?
Minimum 2 methods from each shoe.
Always take multiple test impressions using a minimum
of two methods, from both shoes, even if your scene
impression is clearly from one shoe or the other.
60
What 4 aspects of randomly acquired characteristics contribute to the uniqueness of an outsole?
Size
Shape
Location
Orientation
61
Footwear - Aspects to consider for class characteristics?
Tread pattern
Size
Shape
62
What are schallanach abrasions?
Microscopic pattern formed as smooth rubber of outsole slides over rigid surface
Similar in appearance to friction ridge
Unique and highly discrimating
Changes rapidly over time
63
What is class characteristics?
Intentional or unvoidable characteristics that repeat during manufacturing process and shared my more than one shoe
64
What is meant by the term "wear" for footwear?
The effect of erosion of an outsole caused by friction and abrasions between the outsole and the ground.
65
What is the inversion effect (footwear)?
Can occur in 3D impressions illuminated by oblique lighting
- indented areas appear raised
- turn image 180 degrees to see properly
- does not interfere with examination or interpretation
66
Methods to create 2D impressions?
- chemical pad and paper
- black powder and flexi vinyl
- black powder and transparent film
- ink and paper
- large hinge lifters
- oily residue and black magna powder
67
Methods to create 3D impressions?
- bio foam
- sculpting putty
- Mikro tack
- snow/dirt/mud
68
What are randomly acquired characteristics?
- features that have occurred randomly and or intentionally on a shoe outsole during its use
- RAC's are used to differentiate a given outsole from all others that have the same class characteristics
- when replicated in a crime scene, RAC's contribute toward and are essential in establishing a specific shoe was the source of the impression.
69
3 questions you should ask yourself before making a conclusion for foot wear?
Is there agreement or disagreement in the size, shape and pattern of the class characteristics?
- is there agreement or disagreement in the the wear?
- is there agreement or disagreement in the size, shape, location and orientation of the RAC
69
Indicators of wear
Change in class characteristics
69
What are randomly acquired characteristics
Anything that randomly occurs to the shoe
69
How many randomly acquired characteristics are required to make an ident?
Depends on the size, shape, orientation and location.
For instance- If you see one that looks like someone walking a dog, then see it on the known, you may only need one.
70
Principle of Uniqueness
No two things…
* that happen by chance ever happen in exactly
the same way
Ever break the same way
Ever wear the same way
Ever manufacture the same way
71
What are Class characteristics - physicsl comparison?
* Intentional or unavoidable characteristics
that will be repeated and are shared by
more than one object.
Features inherent in an object acquired
during manufacturing process.
Class characteristics:
Colour, Shape, Size, Style, Model, Pattern,
Diameter, Thickness, Number of
threads/wires/holes, Composition (e.g.,
glass, plastic), Texture, etc…
72
What are Randomly acquired characteristics (RACs): Physical comparison
Something that is randomly added to or taken
away from the original structure of the object
that causes or contributes to making the
object unique from all other objects sharing
the same class characteristics.
Cuts, tears, gouges, wear marks, striation
marks, hackle marks, stress marks,
randomly placed foreign material, etc.
73
Class characteristics- Can they e used to identify/exclude?
Cannot be used to identify.
Can be used to exclude.
74
* Randomly acquired characteristics. Can they be used to identify/exclude?
Can be used to identify or exclude.
75
Why is it important for us to have knowledge of footwear manufacturing?
* To ensure that manufactured class characteristics are not
overvalued as unique features.
* Knowledge of manufactured class characteristics may
assist in excluding a shoe.
* Courts may put more weight on your credentials and
testimony if you demonstrate knowledge of manufacturing
processes.
76
Components of tire treads
Wear bar indicators
Grooves
Lateral Groves
Notches
Rib
Rib elements
Tread widths
Sipes
77
In Tire size P225/65R17, what does P225 stand for?
Passenger
Section width measured in MM
78
In Tire size P225/65R17, what does 65 stand for?
Aspect Ratio % in height/width
79
In Tire size P225/65R17, what does R17 stand for?
Rim Diameter measured in INCHES
80
What is Noise Treatment in Tires?
Tires make noise- Designed to quiet the tire. Varied arrangement of different pitch lengths of the tread elements around the circumference of a tire.
81
3 Measurements to take for Tire Track Evidence
Wheelbase, Front track width, Rear track width
82
When measuring tire track evidence, where do you start/stop measuring
Middle to Middle (Middle right tire track to Middle left etc)
83
What do you write down in notes/on impression when taking a tire impression?
Tire brand and model
Tire size
DOT NUMBER
84
What is the Physical Evidence Comparison
Methodology?
We analyze the unknown and the known to
discover the characteristics, compare the
characteristics observed, and evaluate the
significance of the dissimilarities and similarities
to form our opinion.
85
What should be included in a physical evidence report?
* Reports should outline the methodology used.
* They should have a summary of the opinions expressed.
* Include the reasons for each opinion expressed.
* They should include any explanations or qualifications of the opinions to
ensure the report is accurate and complete.
* It should be complete and stand on its own, without further clarification
required.
86
What are the physical comparison principles?
* Principle of Uniqueness
* Principle of Identification
87
What is the principal of identification - physical evidence ?
If proper methodology is followed and there exists sufficient clarity in an object/impression, it may be identified as originating from a particular source.
88
What is the physical evidence comparison methodology?
We analyze the unknown and the known to
discover the characteristics, compare the
characteristics observed, and evaluate the
significance of the dissimilarities and similarities to form our opinion.
89
What questions should you be asking yourself during the evaluation phase for physical comparisons?
* Is there agreement between class
characteristics?
* Is there agreement between RACs?
* Evaluate the similarities and dissimilarities
observed.
* Consider whether dissimilarities are explainable.
* If explainable, why?
* Are any dissimilarities significant?
90
What are 4 conclusions you can reach during physical evidence comparison?
* Inconclusive
* Exclusion
* Similar to
* Identification
91
What are 3 things to consder when comparing Randomly Aquired Characteristics (RACs) ruding a footwear comparison.
Size
Shape
Location
Orientation
92
Something that is randomly added or taken away from the outsole of a shoe is referred to as a randomly aquired characteristic (RACs) and can be used to identify footwear impressions. Of the following options, select the features that would be considered RACs.
- A rock stuck in the tread.
- The shape of a hole worn through the bottom of the sole..
- A cut on the bottom of the shoe
- A dog shaped void in the element of an impression.
93
What are the 5 possible conclusions that can be reached when conducting a footwear comparison?
Indentification
Exclusion
Association of Class Characteristics
Higher Degree of Association
Inconclusive
94
The tire manufacuturers will vary the size of the tread elements on a tire in order to reduce the sound of the rolling tire on ashphalt. This pattern is referred to as:
Noise Treatment
95
A distortion caused by a rock lodged in a shoe's sole would be considered a class characteristic.
T or F
96
What are we trying to avoid during crime scene processesing?
Avoid Cross Contamination of DNA. Use PPE
97
Obtain as much information as possible regarding a major scene, what type of information should you gather?
* Nature of the scene
* Any heath and safety issues at the scene
* Indoor/outdoor scene
* Who is in charge at the scene
* Number of potential victims
* Legal authority to enter and process the scene
* Has the scene been secured
98
2 most often used searches for large crime scenes?
The 2 methods used most often are:
* Zone search (grid)
* Line search
99
What is the timeline for Rigor Mortis? When does it start?
Post-mortem rigor has a gradual onset - it generally occurs within 2
hours after death. Postmortem rigor affects the entire body within 10
to 12 hours and dissipates generally after 48 hours.
100
What is lividity and what can it tell us?
It is the settling of blood after death and can assist with the sequence of events / was the person moved
101
What's one of the first things removed from the scene and what can you do to prepare for measurements after its removed?
The body. Mark head and feet or do a chalk outline.
102
What are some things you can do before the body is removed?
* Forensic Light Source used on body (picking and taping)
* Swabbing of any bloodstains that appear inconsistent with the
scene
* Preserve DNA that may be lost in transport
* Bag hands & feet (possibly head) in paper
103
What is hold back evidence?
Its evidence only known by the suspect involved in the crime and Police
Examples of
* Weapon (knife, hammer, gun, caliber of weapon)
* Wound (location/type)
* Manner that body was left (clothing on the body, anything unique
done to the body)
* Location (crime scene, body dump)
* Items located at crime scene (duct tape, knives, damage)
104
Why do we take fingerprints at Autopsy?
Obtain fingerprints and palm prints of the victim.
* To identify prints at scene to the victim.
* To identify the victim.
* To conclude FPS file.
105
Subject Matter experts available during Major Crime Scenes?
* Bloodstain pattern analyst
* Forensic entomologist
* Forensic anthropologist
* Forensic archeologist
* Forensic pathologist
106
What can we do when examining a Suspect for evidence?
* Photograph the suspect BEFORE anything is seized or swabbed.
* Examine hands, face, exposed skin for injuries.
* Photograph with scale
* Swab bloodstains
* Powder residue – is GSR kit an option
* Take appropriate samples (hair, saliva, blood, nail clippings)
* General Warrant, DNA Legislation, Incident to an offence
Suspect
107
What is IR (Infrared) and what is it good for?
Powerful, non-destructive search technique for:
- bloodstains on dark or patterned surfaces,
beneath painted surfaces, or on burned
surfaces
- gunshot residue or fingermarks on dark or
patterned surfaces
- poorly visible, modified, or laser-removed
tattoos
- bruises and bite marks
108
Where does IR fall on Wavelength in NM
700-1000 (not visible to human eye)
109
What is BLOODSTAIN PATTERN
ANALYSIS?
Bloodstain Pattern Analysis (BPA) is the study of the
shape, sizes, location and distribution of bloodstains in
order to provide an interpretation of the physical
events that gave rise to their origin.
110
What makes up the Blood constituents:
* Blood plasma (fluid) 55%
* Erythrocytes (red bloods cells) ~45%
* Leukocytes (white blood cells) <1%
* Thrombocytes (platelets)<1%
111
Where is DNA located in blood?
White blood cells
112
BPA may be used to determine:
The direction a blood droplet was travelling when deposited onto a surface;
The origin / source of blood at the scene;
The minimum number of impact(s) to a source of blood;
The mechanism(s) which contributed to the creation of the bloodstain(s);
The relative position(s) of person(s) and/or object(s) during bloodshed;
Movement of person(s)/object(s) during and after bloodletting event(s);
Sequence of event(s) associated with a bloodletting incident;
The agreement or disagreement of bloodstain evidence with statement(s)
provided.
113
THE PREMISES OF BPA
Bloodstain patterns are predictable and reproducible.
114
What is a bloodstain?
Bloodstain: a deposit of blood on a surface;
115
What is a Spatter stain
A bloodstain resulting from an airborne blood drop created when external force is applied
to liquid blood.
116
Blood spatter PHOTOGRAPHS NEED TO BE TAKEN
__________________ TO THE
SURFACE!!!
PERPENDICULAR
117
2 Blood enhancement Chemicals
Amido Black
Aqueous Leuco Crystal Violet (ALCV)
118
Blood Search Tools
Luminol or Bluestar
119
What are 3 bloodstain categories?
- passive category
- transfer category
- spatter category
120
What is the definition of bloodstain pattern?
a grouping or distribution of bloodstains that indicates through regular or repetitive form, order, or arrangement, the manner in which the pattern was deposited.
121
What are examples of passive category bloodstains?
Drip stain, drip trail, drip pattern, splash pattern, pool, saturation stain, flow
122
What are examples of transfer category bloodstains?
transfer stain, swipe, wipe
123
Define a blood spatter stain?
a bloodstain resulting from an airborne blood drop created when external force is applied to liquid blood.
124
Define a passive category bloodstain?
bloodstain pattern created or formed due to the force of gravity on the liquid blood
125
Define a transfer category bloodstain?
created when a wet bloody surface/object comes in contact with another surface. A portion of the original surface may be observed in the pattern.
126
What are 3 methods to calculate the area of origin of an impact bloodstain pattern?
● Stringing method;
● Tangent method;
● Specialized software
127
What health and safety precautions should you take in a blood scene?
Protective tyvex suit
booties
gloves
mask
128
What type of things should you note regarding bloodstains at a scene?
number of stains observed
size and shape
location including measurements of where on the surface and what kind of surface (textured, shiny, porous)
129
What should bloodstain photographs include?
overall of pattern area
midrange of pattern
close up of particular characteristics you want noted
130
How does the blood reagent "aqueous amido black" react to blood?
It dyes the proteins in blood
131
What part of the blood does aqueos leuco crystal violet blood reagent react with?
Heme in the blood
132
What in the blood does luminol / bluestar react to?
luminol is very sensitive and can detect the iron in hemoglobin
133
What type of samples are collected at an autopsy?
Toxicology, DNA/Biology
134
What is our job at an autopsy?
Photography and collect samples. We do not write anything down.
135
It is our job to make notes and come to conclusions at autopsies.
T or F
F
136
What are two measuring methods for plan drawing?
Baseline or X-Y
Triangulation
137
What are two techniques for measuring outer walls - plan drawing?
Additive
Continuous
138
What should you bring to court - plan drawing?
- Bring all the hard copy measurements with you - your sketch is part of your notes
- Bring a ruler so you can obtain measurements or distances from your plan if you are asked
139
What results will you obtain by sending your scene footwear impressions to CPSIC?
- possibly identify the make and model of footwear that created the crime scene impression
140
What results will you obtain by sending your tire track measurements to CPSIC?
a list of possible vehicles that may have created the tracks
141
When requesting a search from CPSIC what should the email include?
- overall image of location of impression
- calibrated original ACAP image
- calibrated / enhanced ACAP image with black tread
Provide a brief case description, including type of offence, substrate and matrix.
