Crime Scene Analysis
SUPA Forensics CSI
Mike Revenson
Mahopac HS
CSI: This ain’t Las Vegas
What we really do!
Types of Crime Scenes
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Open Crime Scene:
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Closed Crime Scene:
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Outdoors; In the Field
Enclosed area; In a room or house
Conveyance:
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Any object that moves/is movable (i.e.,
car)
Have I just walked onto a
crime scene?
What Is A Crime Scene?
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A dynamic environment which begins to
CHANGE immediately after the criminal
action occurs.
The longer the interval between the
crime and the investigation … the less
the scene resembles the original.
Will you be able to solve one of
life’s long unanswered questions?
Are these hardened criminals?
Are you missing something at
first glance?
Things aren’t always as they
seem
Always remember…
This is NOT “CSI”
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Forensics shows are tainting our
students, jury pools, and judges.
Evidence can not be found, processed,
and brought to court for a conviction in
about 42 minutes as on TV.
GOAL
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Recognize
Document
Collect
EVIDENCE
Types of Evidence
Circumstantial:
indirect evidence
Direct
firsthand observations:
- used to imply but prove a fact
- may link a suspect and a crime scene
ex. Suspect’s gun found at crime scene
-eyewitness accounts
-dashboard video
Physical:
cameras
Impressions, Fibers,
-confessions
weapons, bullets, shell
casings
reduces number of
suspects to group
Biological :
may make group of
suspects very
small or even one
individual
Body fluids, hair,
plant parts,
Approach
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(We haven’t entered the scene yet)
A calculated, methodical approach is
best.
Start from the outside and work your
way in if possible.
DOCUMENT EVERYTHING
Mobile crime
scene laboratories
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Protect the scene, photograph, evidence
collection and packaging, latent
fingerprinting.
Microscopic or Undetectable at the scene
Ex. Hair, blood, fibers from clothes, Fabric
impressions, traces of paint
DO NOT carry out the functions of a
chemical lab
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Crime scene search vehicles
Protect the scene
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Every time someone enters or leaves
the crime scene, they deposit and take
evidence with them.
This can be done knowingly or
unknowingly.
Locard’s exchange principle
Protect the scene
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The first person on the scene needs to
seal the scene off with barrier tape.
Where does the scene start or end?
Locard’s exchange principle
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Traces of physical materials (trace evidence) no matter how
minute can tell a story.
Trace evidence is factual. Unlike humans, it cannot be confused
by the excitement of the moment, and it does not forget. It’s a
silent witness that speaks when humans cannot.
Physical evidence cannot be wrong, it cannot lie, it cannot be
wholly absent. Only human failure to find it, study and
understand it, can diminish its value.
http://en.wikipedia.org/wiki/Locard's_exchange_principle
You’re now linked to the crime
Mechanism of Transfer
Example
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9 a.m. -- hair falls from my head to floor
2 p.m. -- stranger walks across floor & hair picked up
on shoe
7 p.m. -- hair is removed from shoe in an investigation
Future time -- comparison of hair on shoe & reference
hair from my head shows them to be indistinguishable
Mechanism of Transfer
Example
Might infer that I and the person
wearing the shoe were in contact
A WRONG INFERENCE
Strength vs. Significance
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Significance of an association uses a wideangle lens & includes the circumstances of
the crime.
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a fingerprint on the outside of a stolen car is
meaningless
a fingerprint on the steering wheel of the stolen
car is highly probative
OK … so how do we minimize items
that can damage our scene?
Scene boundaries?
Is the scene safe?
Scene safety
Boston Slideshow
http://slideshow.nbcnews.com/slideshow/ne
ws/boston-marathon-bombing-51547100/
Crime Scene Safety
The CST must be aware of exposure to diseases which may be present at
scenes:
Anaphylactic shock
Hanta virus
Lyme disease
Meningitis
Plague
Poison oak
Pulmonary
tuberculosis
Rabies
Rocky Mountain Spotted
Fever
San Joaquin Valley Fever
Scabies or Mites
Snake Bites
Spider Bites
Tetanus
Safety
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Crime scene safety ALWAYS a concern!
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Hepatitis, HIV, AIDS, Bio-hazardous pathogens
Impurities can harm us and damage our evidence
(Bacteria, Mold, Fungus)
Use forceps, doubled gloves,
tyvek or kleengard type suits
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What kind of precautions
are needed?
Precautions in lab too
What kind of precautions
are needed?
Don’t end up like…
Chain of custody
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NOTHING IS MORE IMPORTANT THAN:
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The chain of custody
A record denoting the location of the
evidence
Chain of custody label
Is EMS needed?
Who’s allowed on
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To prevent the Locardian transfer of
evidence, only those who need to be on
the crime scene should be allowed on.
EMS first, then continue to document
Securing the Scene
• First responding
officer’s job
• #1 SAFETY
• #2 Preserve
evidence
– Protect area
– Limit exchange
– Request team
Separating the Witnesses
3rd priority; try to prevent collusion
– Ask the following questions:
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When did the crime occur?
Who called in the crime?
Who is the victim?
Can the perpetrator be identified?
What did you see happen?
Where were you when you observed the crime
scene?
Create a permanent record of
the scene
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Pictures
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Video
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Rough and smooth sketches
Record the scene
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Document the scene
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Failure to properly document evidence in
context may negate its probative value.
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Need proof the evidence was where you said
you found it.
Record Crime Scene
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Record the Environment
Record Crime Scene
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Report the Event
Record Crime Scene
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Relate the Evidence
Record Crime Scene
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so that others can…
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Re-view
Re-construct
Re-assemble
Re-visit
Re-tell
Re-inspect
Re-create
Pee Wee Herman says, ”Take
a picture, it will last longer.”
Photographer
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An experience forensic photographer.
Taking pictures of the overall scene as
well as close ups with a scale (ruler) in
the shot.
Crime Scene Photography
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Photography
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Records everything on the scene.
Factors such as lighting and angle may cause
misinterpretation.
Written documentation of lighting and angle are needed.
Crime Scene Photography
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Lens Type
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Wide angle
Normal
Telephoto
Macro: used for close-up/1:1
Lens Speed – f/stop
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f/2.8=15-20; f/4=15-23; f/5.6=15-25
Smaller the number, Larger the field of light
Crime Scene Photography
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Initial frame of film should contain
information about the crime scene:
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case number
date
address
name of person taking photograph
agency, etc.
Crime Scene Photography
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Different photos need to be taken:
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Location (An aerial photo can be sufficient)
Overall
Close-up
Evidence
Close up
Sounds too easy…
Forensic photography is a course in itself.
Pictures can be altered.
A scale is always needed in a picture
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Proper Technique
(Courtesy of Phil Orlando)
38 Caliber and 44 Caliber
Gate Keeper
(we’re getting closer to
entering the scene now)
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Everyone wants to be Grisom from CSI.
He can walk onto a scene and find that
one needle in the haystack instantly.
The gatekeeper must keep EVERYONE
back except for those needed
Frye vs. Daubert
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Frye (1923) – Generally accepted by
the scientific community.
Daubert (1993) – Is reasonable. Judge
is the decider (gate keeper) of that
information.
Who’s needed?
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We already mentioned EMS
Photograph. This way if something is moved,
we have a permanent record of it’s location.
Sketch “artists”
Let’s get organized
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Team Leader
Photographer and note taker
Rough sketches and note taker
Measurement teams and note takers
Evidence recovery and documentation
Team leader
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In charge … the buck stops here
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Responsible for all team members
Rough sketch artist
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Sketching the crime scene – pencil and
paper
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Advantage of selective seeing
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Emphasize items of importance
Later we will add in measurements and
draw it to scale in a smooth sketch
Record The Scene
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Videography
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Can provide a running commentary
Can record in extremely low light
Inappropriate comments can appear on
tape
Notes
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Record of actual measurements of the
scene, evidence and relationship between
them.
Measurement teams
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One word … TRIANGULATION.
Measurement - triangulation
What do I look for?
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We haven’t entered the scene yet.
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LOOK AROUND!
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Who belongs, who doesn’t. Many
arsonists hang out to see the
excitement
Who/what belongs or doesn’t belong
An alert homeowner notices
something that “Doesn’t belong”
Inside a building or room
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Lights on / off ?
Drapes open / closed ?
Windows?
Heat / AC ?
Use all 5 senses to pick up clues
Evidence left over
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Blood stains and splatter patterns
Evidence of a struggle (fingerprints,
DNA, fingernail scrapings)
Arson? Accelerant samples. Family
pictures and heirlooms present?
Ski mask.
A single match stick.
Trace evidence:
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•
•
•
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•
•
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Pet hair on clothes or rugs
Hair on brush
Fingerprints on glass
Soil tracked inside on shoes
Drop of blood on t shirt
A used facial tissue
Paint chips
Broken glass
Fiber from clothing
HOW did the evidence get there?
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Transfer
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Locard’s Exchange Principle
Evidence left over
Evidence left over
Evidence
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Identification
placing objects in a class
Individualization
narrowing the class to one
Fundamental Concepts of
Forensic Science
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Association
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linking a person with a crime scene
Reconstruction
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understanding the sequence in which
events occurred
Vacuum Sweeping
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Critical areas of a crime scenes should
be vacuumed and swept.
*Looking for traces evidence.
Note takers – the most
important job
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You will never remember everything,
especially years later.
Prepare a narrative as you look at the
scene. Note what you see, hear, smell,
taste etc.
Note takers
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Take names and descriptions from
‘Eyewitnesses’
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Vehicle VIN #’s
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More?
Everyone needs a note taker
Conduct an organized search
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Develop a general theory of the crime.
Use this to assist in your search for
evidence.
Choose an appropriate search
Wear Personal Protective Equipment
such as gloves, goggles, Tyvek suits.
HIV, HBV, TB
Search Scene
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Take aerial photographs and/or use
topography maps which can give
another view to the crime scene layout
Best time to perform crime scene
searches is during the daytime
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Why?
Search Scene
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Be careful and be systematic
Check for: point of entry, point of exit
and where particular evidence is located
If possible, have one CST photograph
and another document
Think about
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Who did it?
What happened?
When did it happen?
How did it happen?
Did it happen here or was another crime
scene involved?
Who is the victim?
Why was this crime committed?
What evidence is there to help prove the
motive and the crime?
Conducting the investigation
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Formulate a plan
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Choose areas to be searched
Determine the order of the search
Methods of preservation
Are specialist or special equipment
needed?
Keep an open mind
Line search
Spiral search
Grid search
Evidence
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Who
What
Where
When
How
Log it
Chain of custody report
Chain of Custody
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Proves that the evidence that is collected, is
the SAME evidence that will be used in court
The first person who comes in contact with
that evidence should fill out a chain of
custody tag.
Anyone else that uses that evidence must log
in to say the evidence was in their “custody”.
Packaging crime scene evidence
Packaging crime scene evidence
Packaging crime scene evidence
Chain of custody label
Evidence
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Be sure to collect known standards.
Controls as well as variables. Burnt
section of floor and unburnt.
Evidence
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Packaging requirements?
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Paper, Plastic, Metal can?
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Do not handle excessively.
Marking Evidence
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Marking and tagging
evidence allows the CST to
positively identify the
evidence at a later date
When item cannot be
marked, place in a (proper)
container, seal and mark
with your initials and date
If items with same
appearance are collected,
place an identifying # on
each item and indicate # in
your notes
Packaging Evidence
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Each item should be
packed in separate
containers to avoid
damage, loss or
contamination
Small items (i.e., paint
chips, hair, fibers, spent
casings, etc) should be
placed in small
containers or druggist
folds (a.k.a.
pharmaceutical fold)
Packaging Evidence
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Items with fingerprints should be packaged to avoid
damage to prints ~ Fasten object in container so it
doesn’t shift in transit
Packages should be sealed and marked with your initials
and date collected
Biological evidence such as
dried blood should be
packaged in paper ~ Liquid
blood can be collected in a
glass tube but SHOULD NOT
be frozen
Evidence log and Chain of Custody
document in attached to the
evidence container.
Contains
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Case number
Item inventory number
Description of the evidence
Name of the suspect
Name of the victim
Date and Time of recovery
Signature of person recovering evidence
Signature of any witnesses present during collection
Crime Object/Suspect Object
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Crime Object
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An item from the crime scene
Questioned (unknown) sample
The object for which we would like to
establish an origin and associations to help
in reconstructing a time line.
Crime Object
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Examples
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Fibers on a victim’s body
Fingerprints at the scene
Bullet recovered from a body
Crime Object/Suspect Object
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Suspect Object
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A known comparison object
A reference sample for which the origin is
known
Used to establish the identity, source,
individuality and associations of the crime
object.
Suspect Object
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Examples
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Reference blood sample from a suspect
Carpet fibers from a house or car
Fingers of a person
Gun recovered from an individual
Evidence Collection
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Area collection
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Photography or videography
Blood spatter patterns and prints
Gives spacial relation to the scene
Prints or blood spatter may be visualized or
enhanced with chemicals.
Analyze back at the lab
Pressure cooker parts from
Boston Bombing
Back to…”Is the scene safe?”
Time of death?
Is something odd here?
When in doubt, call THE PRO
When complete
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Release the scene. Note time, agency,
and person in charge
Follow directions … don’t poke your
nose into things you shouldn’t
Doors
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Locked or bolted from the inside or
outside
Forced entry?
Doorbell work?
Scratches around keyhole etc?
Windows
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Type
Locked?
Open?
Broken?
Position of drapes, curtains, blinds.
Mail
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Opened?
Newspapers
Check postmarks on mail and dates on
newspapers.
Lights
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Which ones were on?
How are they controlled? Timer,
motion sensor, switch?
Bulbs broken or unscrewed?
Still warm?
Smells
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Gas
Tobacco
Alcohol
Perfume
Gun powder
Anything Unusual?
How does one change into another,
and no one notices for a while?
Kitchen
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Was food being prepared? Match with
victims stomach contents.
Partially eaten? Utensils.
Stove warm or still on?
Attempts of burning or washing away
evidence?
HVAC
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Type
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Vented? (CO)
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Thermostat setting
Party?
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Empty bottles. Note labels, brands,
types of liquor.
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Tables.
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How many cups.
Ashtrays
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Cigarette packs and butts; brand
Lipstick
Tooth marks
DNA from butts
Trash cans
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Contents
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Look disturbed?
Clocks
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Time on clocks, VCR etc.
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Right time?
Bathroom
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Vanities and towels damp to touch?
Bloodstained?
Signs of cleanup
Toilet sat up or down?
Check toilet tanks – great hiding place.
General housekeeping
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Evidence of a struggle
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Neat and clean or dirty or combination.
Shootings
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Cartridge casings - # and location
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Holes - #, location, angle.
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Blood splatter
All over
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Footprints
Finger prints
Debris
Discarded items
Attempt to determine the route used to
enter and exit the scene
Now try to do this with 30
Students!!!
We Know better
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Team leader
Photographer
I/O’s
Sketch
Measurement team
Evidence documentation and collection
Other Crime Scene Personnel
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ID Techs/Fingerprint
Examiners
Sketch Artist
Videographer
Crime Lab Analyst
M.E./Coroner/Forensi
c Pathologist
Doctors/Nurses
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District Attorney
Forensic
Odontologist
Anthropologist
Psychologist
Forensic Engineer
Audio Specialists
Toxicologist
Firearms Expert
Crime Scene Investigation Team:
• Police Officers: usually first (possibly a DA for a search warrant)
• Crime Scene Investigators: document crime and collect physical
evidence
• Recorder
• Sketch artist
• Photographers
• Evidence collectors
• Medical Examiners: coroners may be necessary to determine
cause of death in a homicide case
• Detectives: look for leads, interview witnesses and talking to the
CSI about evidence
• Specialists: entomologists, psychologists
7 S’s of CSI
1.
2.
3.
4.
5.
6.
7.
Securing the Scene
Separating the Witnesses
Scanning the Scene
Seeing the Scene
Sketching the Scene
Searching for Evidence
Securing and Collecting the Evidence
Recent Cases
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Elderly man in Long Island found
February 2007 dead in his chair with
the TV on. Doesn’t sound so odd …
EXCEPT the time of death was
estimated at December 2005.
http://www.foxnews.com/story/2007/02/18/70-year-old-man-founddead-in-front-tv-year-later/
Legal Aspects
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If searching a crime scene, you
need proper authority to do so -- plan and coordinate!
Get your search warrant!!!
Otherwise, evidence will become
“fruit of the poisoned tree”
In murder cases, the statute of
limitations never runs out!
Michigan vs. Tyler
Mincey vs. Arizona
Legal Aspects
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Exceptions:
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Plain View
Victim is sole occupant/owner
Incident to Arrest
Consent from Victim/Subject
Crime Scene Admissibility
Michigan v. Clifford
Michigan v. Tyler
Mincey v. Arizona
Crime Scene Admissibility
Michigan v. Clifford Investigators searched an arson fire scene five
hours after the fire was put out, without
consent or warrant. Incriminating evidence was
recovered and used in the conviction.
The US Supreme Court reversed the decision
citing the need for a warrant five hours
after the fire was put out.
Crime Scene Admissibility
Michigan v. Tyler Arson investigators conducted three separate
searches of a fire scene. The first was one
and one-half hours after the fire, but dense
smoke caused the search to wait until four
hours later (the second search). The third
search was weeks later. Evidence from the
first two searches was held admissible, but
evidence from the third search was excluded.
Crime Scene Admissibility
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Mincey v. Arizona –
investigating the shooting death of an undercover police
officer in the residence of the suspect.
* The police established a crime scene, conducted a
thorough search of the scene and found evidence of other
crimes.
** The police charged the suspect with those crimes as well
and the court rejected it.
*** The court recognized the need of the police to control
the situation upon their arrival, and the need to establish a
crime scene. But as soon as there was no more danger of
evidence loss, removal or destruction, there was ample time
to obtain a search warrant, particularly when evidence of
other crimes was inadvertently discovered
Legal Considerations at the
Crime Scene
Two cases were decided in 1978 on these
issues:

Mincey v. Arizona – The court decided
that a 4-day search following a warrantless
entry in response to an officer- involved
shooting was not legal and the evidence
obtained which was used to convict Mincey
was thrown out and the conviction was
overturned.
Legal Considerations at the
Crime Scene
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Michigan v. Tyler – Following the burning of a
building, three additional searches of the premises
turned up evidence of owner-initiated arson. The
court ruled that the three subsequent trips into the
premises without a warrant being obtained were
illegal searches and the conviction was overturned.
The search of the buildings following the initial
response to the fire was allowed though warrantless
since it immediately followed the initial entry by
firefighters
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WHAT HAPPENED
HERE?
Example
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If the evidence & reference also share
class characteristics with other items of
similar manufacture
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the comparison between them can only
determine that a common origin cannot be
eliminated
other reference materials not examined but
known to exist cannot be eliminated as
source
Individualizing Traits
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Minutiae of friction ridges on fingers
(fingerprints)
nicks, cuts or gouges in a tire
fine striae in the barrel of a firearm
DNA markers
Association
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A pairwise relationship between two different
objects that may be linked through a
common piece of evidence
The first step in interpreting analytical data in
the context of the crime
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An association infers that two objects were at
one time in contact
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results directly from the ID or individualization of a
crime object and a reference object
Example
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The microscopic traits of an evidence hair
found on victim’s shirt (evidence: the crime
object) are compared to hair standards
collected from the suspect (reference: the
suspect object)
The traits of the evidence hair are exhibited
by the reference hair
The evidence and reference hairs are
indistinguishable
Mechanism of Transfer
Example
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9 a.m. -- hair falls from my head to
floor
2 p.m. -- stranger walks across floor &
hair picked up on shoe
7 p.m. -- hair is removed from shoe in
an investigation
Future time -- comparison of hair on
shoe & reference hair from my head
shows them to be indistinguishable
Mechanism of Transfer
Example
Might infer that I and the person
wearing the shoe were in contact
A WRONG INFERENCE
Strength vs. Significance

Significance of an association uses a
wide-angle lens & includes the
circumstances of the crime


a fingerprint on the outside of a stolen car
is meaningless
a fingerprint on the steering wheel of the
stolen car is highly probative
Conclusion
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An association between two objects
leads to an inference of contact
the shared traits on which an
association is based may fall anywhere
on the continuum between ID and
individualization
The rarer the characteristics
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the stronger the association
the stronger the indication of contact
Reconstruction
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Ultimate goal of a forensic investigation
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deduce what happened
the order of events
Placing the associated evidence and
reference items into their appropriate
place in time & space
Reconstruction
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Is not a videotape replay of the events
of the crime
Involves the juxtaposition of two or
more objects (people are a subset of
objects)
At best, it describes the relationship
between several different items of
evidence with some effort to place them
in sequence
Reconstruction



Each association established using the
tools of ID and individualization
represents a point in time & space
An attempt is made to order these
points logically in sequence & time
The investigator can’t know what really
happened in between the points
Summary

The key to a competent forensic
examination


asking the right (relevant) legal and
scientific question
understanding the limitations of the
analysis
SUMMARY
• Locard’s principle
• Evidence may be direct: eyewitness or Circumstantial:
does not directly prove a fact
• Evidence can be physical or biological (trace can be
either)
• CSI team: police officers, detectives, CSI investigators,
medical examiners and specialists
• CS investigation: recognizing, documenting and
collecting evidence from a scene
• First responding officer: id extent of crime scene
(including 1 and 2), secure the scene and segregate
witnesses
• walk the scene, id evidence then document scene by
photos and sketches
• Evidence must be properly handled, collected and
labeled to maintain Chain of Custody
• Evidence is analyzed in a forensic lab, results provided
to detectives who fit results into crime scenario
Lets get to it
Google Sketch –
Courtesy Scott Rizzo