Midterm Flashcards
Forensic Science
Application of science to matters of the law
Law in Canada:
Common Law (all provs/territories)
Common law:
derived from judicial decisions of courts and similar tribunals
Criminal Code:
“An act respecting the criminal law”
- defines criminal acts and procedures in Canada
Locard’s Exchange Principle:
- every contact leaves a trace
- when two things come in contact there will be exchange
- founding concept in Forensic science
Define a crime scene:
any physical scene that may provide evidence of a crime
- may include vehicles, buildings, human bodies, open air sites, water locations
Define crime scene evidence:
physical items, often referred to as exhibits, recovered at or in relation to a crime scene
- fingerprints, dna, etc
- given a lot of value in court
Scientific method:
Observation
Formulation
Use of Hypothesis
Experimentation
Crime Scene Investigation:
Key part of an investigation
- keep an open mind about the scene
- locates, documents and seizes possible evidence
- CSI should be at arms length from lead investigator to avoid bias
Brendy Waudby
Wrongfully convicted of murdering her young daughter
- evidence from autopsy, a hair
- Peterborough 1997
Paul Bernardo and Karla Homolka
missed video tapes lead to karla’s 13 year sentence
- St. Catherines, 1993
Forensic Identification (Crime Scene) Services
- support service
- respond as requested
- may respond to all levels and types of occurrences
Crime Scene examiners are responsible for:
recording, documenting and examining the scene
-collection and preservation of evidence
submitting exhibits for further examination/processing
-testifying in court
- no tunnel vision
CSI
crime scene investigator
FIO
forensic identification officer
FIA
forensic identification assistant
SOCO
scenes of crime officer
FSA
forensic services assistant
SCS
scenes of crime specialist
CSST
crime scene support technician
Investigative notes are a permanent written record of:
- the facts of an investigation
- your actions in an investigation
- an important tool to assist you in providing accurate and factual information to an investigation
notebook:
an official legal document that contains the details of an investigation
scene photos
- general photos taken of the scene prior to processing
- shows everything as found
- not defined process
- painting a picture
- as found by the police forensic unit upon arrival
exhibit photos
- specific set of photos of an exhibit/object
- follows a defined process
- consists of a series of photos (typically 4)
- area where evidence should be in scene photos
crime scene photographer
- does not need to be professional
- needs to know how to use a camera
- should have formal training
camera technique
- right hand holds camera body by right side
- left hand holds/supports barrel of the lens from underneath
crime scene photo succession
general to specific (overall then individual pieces)
overall photo
need to be taken of any crime scene before any processing can begin
four photographs required for a specific item:
- overall
- mid range
- close up
- close up with scale
crime scene camera
Digital Single Lens Reflex (DSLR)
Charge Couples Device (CCD)
- digital equivalent of film
- CCD contains millions of silicon photo sensors
- image passes through lens and is focused onto a CCD
- exposure is controlled by shutter speed/aperture
JPEG
Joint Photographic Experts Group
- most common image format used in digital cameras
- fast, lossy format
- lose some quality everytime you open/close file
TIFF
Tagged Image File Format
- high quality, large files, lossless compression
- useful when opening/closing files repeatedly
RAW
proprietary format
- original data, no standards
- nikon and cannon have their own format
- has been called the digital “negative”
Exposure
- amount of light that reaches the camera sensor (CCD)
- too much light is overexposed
- too little light is underexposed
Camera settings that affect exposure of an image are:
- aperture
- shutter speed
- camera ISO
Aperture
- size of the opening in the camera lens through which light passes
-F4 lets the most light in
-F32 lets the least amount of light in
Shutter speed
- length of time the camera shutter stays open exposing light onto the camera sensor
- longer the shutter is open, more light reaches the sensor
ASA/ISO (film speed)
- numerical rating that describes the sensitivity to light of CCD
- does not affect the amount of light entering the camera
Depth of field
- distance between the closest and farthest objects in a photo that appear acceptably sharp
- controlled by aperture (f-stop) selection
Depth of field can be affected by:
- distance from the subject to camera
- focal length of lens
Flash techniques
- direct flash
- feathered flash
- fill in flash
- bounce flash
- oblique flash
- multiple flash (on camera)
- multiple flash (off camera)
- ring flash
Direct flash
- flash is pointed directly at the item you want to photograph
Feathered flash
- flash is off camera, held above the lens
Fill in Flash
- utilized on bright days
- flash pointed in direction of shadowed areas to raise brightness level
Bounce flash
- used for less contrast, softer lighting and reducing intensity of the light
- flash head is set to 45 degree angle
Oblique flash
- used when photographing impression evidence
- flash connected to a flash sync cord and held at a 45 degree angle
- used to show detail
Multiple flash (on camera)
- camera mounted on tripod
- flash activated manually
- used for low light/no light scenes
Multiple flash (off camera)
- painting by light
- large outdoor scenes at night with ambient lighting
- camera on tripod
- long exposure time
Ring flash
- circular flash that fits around camera lens
- allows light to spread out evenly
- good for close up
- often used in autopsies
impression evidence
- with and without scale
- oblique lighting
- uses flash
- camera on tripod
- camera and impression need to be on same plane
Tire tracks
- capture as much of rotation as possible
- width as important as pattern
- will need 2 measurements
- scale must be same depth as impression
videos (on camera)
- large scenes/ used to tie parts of a scene together
- should not be narrated
methodical approach to document scene
- overall scene
- show location of evidence with overall and mid range
- show detail by close up with and without scale
3 points of qualification of a photograph in court:
- photo contents must be relevant to the point of issue
- photograph must not be prejudicial to the court or jury
- photograph must be free of distortion and not misrepresent what it purports to show
Define Fingerprint
an impression of the friction ridges of all or any part of the finger
what is SWGFAST
Scientific Working Group on Friction Ridge Analysis, Study and Technology
Palmar vs Plantar
palmar - bottom of hands
plantar - bottom of feet
Finger print Theory
- human friction ridge skin is unique
- human friction ridge skin is persistent throughout the individuals lifetime
When are fingerprints fully formed?
by the time a fetus is 6 months old
- max genetic similarity is in identical twins
Functions of skin (4)
- acts as a container for the skeletal structure and internal organs
- provides sensory input about external conditions (temp)
- provides a means for the elimination of waste products (salt, amino acids, ammonia)
- allows for the ability to grasp surfaces firmly and grip objects
two layers of friction ridge skin?
epidermis (top)
dermis (bottom)
epidermis?
- outer layer of skin
- protective barrier for underlying tissues
- must constantly replace cells leaving surface
- consists of 5 layers
dermis?
- inner layer of skin
- gives skin its flexibility and strength
- contains nerves, sweat glands, and blood vessels
composition of fingerprint secretions
-99% is water
-other 1% contain salts, amino acids and fats
- chemical composition changes with time
3 levels of examining fingerprints:
- pattern
- ridge characteristics
- ridge features pores, ridge edges
finger print patterns
-loop
-whorl
-arch
ridge characteristics
average finger contains 150 characteristics
- ridge ending, dot, spur, delta, etc.
shapes of ridge characteristics
positions of pores, edges, creases and incipient ridges
incipient ridges
friction ridges that didnt fully form
- not used for classification purposes
fingerprint comparison process
(ACE-V)
A- analysis
C- comparison
E - evaluation
V- verification
analysis
- first step of process
- assessment of unknown impression to determine suitability for comparison
- SWGFAST
- if not suitable, examination process ends
anatomical aspects:
how the object was handled and the way the print was deposited
substrate:
the type of surface on which the impression was located and how it impacts the appearance of the fingerprint
matrix:
what material was deposited on the substrate by the finger
deposition pressure:
assessment of downward pressure exerted by the finger on contact with the substrate
lateral/pressure distortion
assessment of movement of the finger while in contact with the substrate
clarity:
visual quality of the friction ridge detail
comparison
-second step of ACE-V
- observation of 2 or more impressions to determine the existence of discrepancies, dissimilarities, or similarities
Comparison should be conducted in what type of manner?
objective
comparison is made from the _____ impression to the _____ impression
unknown
known
Evaluation
- 3rd step of ACE-V method
- examiner assesses the value of the details observed during the analysis and comparison steps to reach a conclusion
- subjective in nature
outcomes of evaluations:
exclusion: not from the same source
inconclusive: unable to identify or exclude as being from the same source
identification: from the same source
identification decision:
-no predetermined, min # of features required to report a decision
- overall assessment
- opinion is subjective and of the examiner
3 types of impressions:
- latent
- visible
- moulded
latent
not readily visible to the naked eye, needs the use of developmental techniques
visible
readily visible without use of developmental techniques
moulded
impressions that retain the 3D shape of the ridge detail within the surface
porous vs non-porous surface
porous: chemical process (paper)
non porous: powders or glue fuming (glass bottle)
powdering:
application of the finely grounded, coloured powder to a non-porous object to make latent prints visible
- powder clings to moisture, oil
brush type:
fiberglass filament brush, camel-hair brush, feather duster
steps to powder:
-apply small amount of powder onto surface
- brush in direction of ridges
- stop when latent print reaches point of sufficient clarity
- print can be overpowdered
marking a fingerprint:
- circle with wax pencil or dry erase marker
- use letter R and #
- date and initials
- scale close to edge of print
photographing a fingerprint:
- overall photo
- mid range
- closeup photo
- close up with scale
lifting a fingerprint:
- use a hinge lifter or roll of tape
- place edge of tape on surface in front of latent print
- apply downward pressure until print is covered
- pull back on tape and place on lift card
exhibits:
- need to be collected in new unused packaging
- PPE
- transported securely and separately to avoid being damaged/cross cont.
- should be dried
- can be stored anywhere from 1 - 100 years
property reports:
hand written
disclosed for court purposes
Purposes of crime scene sketch:
- A record of the size/distance relationship of the CS and evidence
- Clarifies info from photos/videos
- Easiest way to present crime scene layout (measurements)
Rough sketch:
- drawn at scene
- not final version
- done in pencil
- not to scale
- done after photos
- measurements must be accurate
A rough sketch includes measurements from:
- rooms
- furniture
- doors/windows
- vehicles
- roadways
Should include this information:
- date
- adress
- name of person drawing
- direction
- scale
3 measurement methods:
1) triangulation method
2) rectangular coordinate method
3) baseline method
Triangulation Method
- The triangulation method
utilizes two fixed permanent
objects within the crime scene. - Measurements are taken from
each fixed point to each piece of
evidence.
Rectangular coordinate method
- Used when measuring the
distance to an object from two
mutually perpendicular objects - Example: interior of a room
- Useful for indoor scenes
Baseline Method
- Used to measure items of
evidence when there are
various objects in the crime
scene - Lay a tape measure in the
scene (baseline) - Measure exhibits/items off
of baseline at right angles - Useful for outdoor scenes
Scene diagram
- Demonstrative aid
- Not evidence
- Used primarily for court
purposes - Assists with court proceedings
- Helps to visualize crime scene
4 main search techniques:
- line search
- grid search
- zone search
- spiral search
line search
- Accomplished by searchers
moving in parallel, along
defined lanes, in the same
direction. - Each lane is about 1 metre
wide. - Suitable for outdoor areas or
large indoor scenes - Looking for bigger items
Grid search
- Conducted by completing a
line search in one direction
and then completing it in the
opposite direction - Thorough method
- Time consuming
- Resource intensive
Zone search
- Involves dividing an area to
be searched into several
adjacent zones. - Good when searching for
small objects. - Can be done by one or more
searchers
Spiral Search
- Searcher walks in a circular
direction from the inside/outside
to the outside/inside of the area to
be searched - Used when looking for evidence
that is expected to be found within
a specific distance of another piece
of evidence (nearby) - e.g. ejected spent casing near gun
that was fired in that location
Exhibit storage:
- follow up processing of exhibits (drying, packaging, photos)
- Lab submissions (CFS)
- Court (show continuity)
- Exhibit storage (after trial and appeal period)
ALS/FLS
Alternate light source
Forensic light source
- in use for 40 years
- portable
- used in CS and Laboratory
Camera settings needed for als/fls
- Orange filter on lens * High depth of field * Low ISO * Exposure – timed exposure * will need to try different time
lengths (trial and error) to get
the right amount of light - Use the remote shutter release
cord
Anthropometry/Bertillionage:
-1882
Alphonse Bertillon
- system of identification based on 11 body measurements
Book - Criminal investigation
-1891
-Hans Gross
-credited with coining the term “criminalistics”
-first comprehensive description for using physical evidence to solve crime
Exchange principle
-1910
-Edmund Locard
-“locards exchange principle”
-created the first crime lab in France
-extensive work of fingerprints
First US crime lab opened by LA police
1924
AAFS was formed in chicago , began to publish journal of forensic science
1950
Lucas described application of GC
1960
Detection of gun shot residue
1974
development of fingerprints using cyanoacrylate (superglue fuming)
1977
DNA used for first time in criminal case in england - murder conviction
1986
FBI introduced computerized searches of the AFIS fingerprint database
1996
NAS report released - deficiences and inconsistences
2009
Forensic Science in canada (hart house report)
2012
PCAST report discusses various comparison disciplines
2016
Crime scene processing:
- How does it start? Call/Request * Where to start? Think court &
contamination (PPE) - How to gain lawful access to the
scene or item? Authority - What equipment/specialists will
you need? - Follow
-up processing - Lab submissions * Exhibit storage * Court (like a final exam!)
crime scene examiners are responsible for:
- recording, documenting and examining the scene
- the collection and preservation of evidence
- submitting exhibits for further examination (CFS in Ontario)
- carrying out their role independently and without tunnel vision
- being a support service to front line officers and investigators
- testifying in court
3 step process of crime scene examination
1) Learn – gather information/intelligence
2) Plan (Scene Walk Through) – assess, develop plan and prioritize steps
3) Act – processing the scene
step 1 (learning)
a. Speak with first responder(s) regarding their observations/actions
b. Consider possible safety issues at the scene(s)- what PPE is needed?
c. Determine the necessity of obtaining consent to search and/or a
search warrant or what legislation you are relying on (e.g. lawful
authority to proceed)
d. Evaluate and establish a path of entry/exit (common approach path)
to the scene to be utilized by authorized personnel.
e. Evaluate initial scene boundaries
f. Determine the number/size of scene(s) and prioritize
g. Determine and request additional investigative resources as
determined and needed (e.g., personnel/specialized units)*
*This step is ongoing as the investigation unfolds
h. Ensure continued scene integrity (scene security, scene log, crime
scene tape – scene dependent)
step 2 (plan)
- The walk-through provides the first opportunity to see and identify
valuable and/or fragile evidence - Allows for the development of a plan which will provide for a
systematic examination and documentation of the scene - Wear appropriate personal protective equipment (PPE)
- Identify any fragile and/or perishable evidence to be collected first
- Formulate a plan to process the scene by prioritizing steps that will be
taken first - Assign team members roles as needed (Exhibits, photos, notes)
- Develop a general theory (“Hypothesis”) of the crime scene
part 3 (act)
- Photography
- Video (if needed to cover a large scene)
- Notes
- A rough scene sketch with measurements
- Scene examination (Alternate light source, bloodstain pattern
analysis) - Exhibit collection
- Search for further evidence
UAV
unmanned aerial vehicle
- cheaper than usual aircraft
- fast to scene
lawful authority to enter CS obtained by:
- Consent (voluntary ,Wills)
- Search warrant (Criminal Code, Controlled Drug & Substances Act)
- Legislation (e.g. Coroners Act)
Consent - voluntary
- An individual can give voluntary consent to the police to examine
themselves, their vehicle, their place of residence or business - This is how the police typically examine most crime scenes
- Example: Business calls police to report a break and enter (B&E)
- Police attend and with consent of business (owner, manager, or
employee) examine crime scene for evidence (it must be someone
capable of giving consent) - The case, R. v. Wills (1992) OJ 294 (ONCA), outlines the conditions
that must be met in order for an individual to give informed consent
Wills Consent (informed consent)
- The person did consent to the search
- The person has to have the authority to consent to the search
- The person giving consent was aware of what the police were going
to do - The consent was voluntary (no threats or promises)
- The person was aware of the right to refuse to give consent
- The person was aware of the potential consequences of giving
consent
Search warrant
section 487 CC
* Authorizes, for a limited time, the search of a place for the purpose of
seizing “things”
* Police officer, known as the informant, provides the evidence that
gives the issuing justice grounds (“reasonable grounds”) to grant the
order to search
* “Things” does not include drugs
* A separate warrant under the Controlled Drugs and Substances Act
(CDSA) would be required to search for and seize drugs (controlled
substances)
Coroners Act
- Coroner may enter and inspect any place where a dead body is and
any place, based on reasonable grounds, a body was removed from - Can inspect records and seize anything relevant to investigation
- Police must assist Coroner when requested
- Coroner may authorize a police officer to exercise all or any of the
coroner’s powers - This allows police, under direction of coroner, to enter a scene in
order to document deceased in situ and remove them - Does not allow for any other type of scene examination
Primary crime scene
- Location where actual crime or
initial crime occurred - Murder scene – body location
Secondary crime scene
- Location where subsequent
crime or actions related to initial
crime scene occurred - Location where stolen vehicle
was recovered that was used to
flee from murder scene - Body moved to location other
than murder scene
Public areas
- police have right to conduct inv. in public areas such as parks and roadways
- do not need permission to close an area in public domain
impression evidence
- fingerprints
-footwear
-tire tracks
DNA evidence
- blood
- hair
- bodily fluids
Physical evidence
-clothing
- weapons
- tools
- documents
digital evidence
- computers
- security cameras
- cell phones
CFS (centre of forensic science)
- established in 1932
- 1996 renamed CFS
- independent of police and court system
CFS dna sections - High Volume Service (HVS)
- Mainly B&Es , theft , drug
offences, weapons, stolen
vehicles - Only accept:
- Cigarette butts
- Swabs
- Cut outs from envelope flaps
CFS dna sections- Violent crime Service (VCS)
- All primary designated offences
except B&E - Homicides, robbery, sexual
assault
Swab classifications for submission to CFS
1.Swabs of suspected blood (BLS)
2.Swabs of drink containers /
drinking implements (DCS)
3.Swabs of partially eaten food /
eating utensils (FDS)
4.Other ‘saliva’ swabs (SAS)
5.Weapon swabs (WPS) - Guns and
Knives only
6.Airbag swabs (ABS)
7.‘Other’ swabs (OTH)
BLS
- Do not oversaturate the swab
with blood as it can inhibit the
ability to find DNA - If the suspected bloodstain to be
swabbed is dry, use a moistened
swab (distilled water) - If the suspected bloodstain to be
swabbed is still wet, use a dry
swab
DCS
- Only swab those containers that
appear to have been used for
their stated purpose within the
time frame of the relevant
offence - Will require swab to have been
moistened
FDS
- Food partially eaten and utensils
used during relevant time frame - Moistened swab required
SAS
- All other items that may have
come into contact with saliva
and/or nasal secretions - lipsticks
- drug pipes
- suspected spit
- plastic cigarillo tips
- cigars
WPS
- Handled weapons must have
been brought to the scene by
perpetrators during the
commission of an offence.
ABS
- Swab of each deployed air bag
and a separate swab of any
other visible mucous or blood
like stains - Results do not position
occupants in a particular seat in
the vehicle
DNA profiles
submitted to national DNA data bank (NDDB) run by RCMP in ottawa
NDDB assists law enforcement agencies in solving crime by:
1) Linking crimes together where there are no suspects;
2) Helping to identify suspects;
3) Eliminating suspects where there is no match between crime scene
DNA and a DNA profile in the National DNA Data Bank; and,
4) Determining whether a serial offender is involved
DNA identification act:
biological samples collected from
convicted offenders and the resulting DNA profiles can only be used
for law enforcement purposes
COI convicted offender index
electronic
index developed from DNA profiles collected from
offenders convicted of designated primary and
secondary offences
CSI crime scene index
separate electronic
index composed of DNA profiles obtained from crime
scene investigations
United states - CODIS
- FBI’s Combined DNA Index System
(CODIS) - Became fully operational in 1998
- Allows federal, state, and local crime
laboratories to exchange and compare
DNA profiles. - Investigative leads come from 3 indices:
Forensic, Offender and Arrestee.
United kingdom - national DNA database
- World’s first national database (1995)
- Contains > 4 million profiles
- It is the oldest and most inclusive national
forensic DNA database in the world - Includes DNA samples from 2.7 million
individuals—about 5.2% of the UK
population - Effective April 2004, DNA allowed to be
collected on arrest rather than on charge
(England and Wales, not Scotland)
interpol data base
- Automated DNA database is called DNA
Gateway (2002) - Member countries submit profiles
(offenders , crime scene, missing persons
and unidentified remains)
