Transcript The Crime Scene A look into evidence gathering and processing Mrs. Toth

The Crime Scene
A look into evidence gathering and
processing
Mrs. Toth
Some slides by Mrs. Ryan
Crime Scene Definition
Crime Scene vs. Scene of the Crime
Includes planning areas,
flight paths, staging
areas, surveillance
Location of the actual
crime
What is the Job Title?
• In the United States, crime scene
investigators are usually called
“criminalists”
• In the United Kingdom, crime
scene investigators are usually
called
“scene of crime officers”
What is the Job Title?
• Job titles in forensic fields vary widely
from jurisdiction to jurisdiction
• Example: A crime scene analyst is a
civilian employed by the police
department in Las Vegas
- allowed to carry guns
- depending on the department,
analysts can be civilian or law
enforcement
What is the Job Title?
• In Albany, 8 detectives make up a
“support unit” that collects all
areas of evidence instead of
individual units
Lockard’s Theory: Review
• Dr. Edmund Locard’s theory for the
exchange of evidence is widely
recognized as the cornerstone of
forensic science.
• Locard’s theory: Whenever two objects
come into contact, a transfer of
material will occur. Evidence that is
transferred can be used to associate
objects, individuals or locations.
Lockard’s Theory: Review
Through evidence, try to connect the:
Victim
Suspect
Crime Scene
Every contact leaves a trace…
Examples of trace evidence that is picked up or left behind:
• Hair, Fibers
- From the individual,
their spouse, child,
pets, victim, etc.
• Soil, sand, plant
matter, sawdust
- Picked up on a
person’s shoes
Class versus Individualized
Evidence
• Class evidence - evidence that can only
be grouped into a general category;
cannot be pinpointed to a direct person
or object
ex. Black Lab Hair
• Individualized evidence - evidence that
can be pinpointed to only one individual
or object; unique
ex. Fido’s hair (a black Labrador)
through DNA
Class versus Individualized
continued
Trace Evidence
Hair
Class
Dog Hair
Black Labrador
Retriever Hair
DNA from hair individualized
to Fido (a black Labrador
Retriever)
Individualized
Class versus Individualized
continued
• A single piece of class evidence
can rarely convict someone,
though it may exclude a suspect.
• However sheer numbers of class
evidence can make coincidence
unlikely.
Ex . Porco case
“Common Source” Not
“Match”
• When two objects share a class identity
• For example, white tennis shoes
– The “common source” can be the factory,
owner, or even where found
– Suspect owns white tennis shoes and one is
left at crime scene; try to see if the CS shoe
came from a “common source” as the one
in his apartment
• Example, fibers on a body in ditch
– Fibers on body belong to an automobile
– Find a suspect, try to see if fibers in his car
are from “common source” as the fibers on
the body
Evidence Types
Evidence
Direct
Circumstantial
Biological
Physical
Evidence Types
1. Direct Evidence: evidence that, if
true, proves an alleged fact, such
as eye witness account of a crime
Ex. Police dashboard video cameras
Witness testimony
Evidence Types
2. Physical or Real evidence (A type of
indirect evidence): A tangible object
related to a crime.
Ex. Bloody knife at crime scene
3. Testimonial evidence (A type of direct
evidence): Verbal accounting of an
incident by a witness, victim or
suspect.
Ex. Neighbor says they have seen Suspect A with a
knife at their house
Evidence Types cont.
4. Indirect or circumstantial: evidence
that supports other evidence; implies
or infers facts; secondary
Ex. Suspect A has expert training in knife skills;
victim was stabbed to death in a technical
manner
Value of Evidence
• Physical evidence: Cannot lie, die,
quit, forget ….etc.; very good
evidence!!!
• Testimonial evidence: may change,
be unreliable, be mistaken or source
can become unavailable during the
case; questionable and therefore not
reliable!!
Physical Evidence Issues
Often…
•
•
•
•
•
•
Not recognized, identified or overlooked
Not legally collected
Not properly collected and/or packaged
Not properly stored
Not properly tested
Chain of custody issues
Maintaining a Chain of
Custody
• As evidence is collected, the
evidence bag is initialed by the
collector and dated
• Anyone who possess the evidence
during the investigation must sign
for it as a record
• Failure to document can have
evidence excluded from case/trial
Evidence Issues continued
• Most of the mistakes made in the
collection, securing and testing of
evidence can be attributed to the
lack of training and understanding.
Ex. OJ Simpson Case
- mishandled evidence
Jon Benet Ramsey
A Forensic Nightmare
John and Patsy Ramsey
Jon Benet’s parents
The “War and Peace” of
Ransom Notes
The Ramsey House
Jon Benet’s neck at
autopsy
The garrote made from a
broken paintbrush
The Autopsy Report
Jon Benet’s Grave
Why have protocols?
• The errors made in the Jon Benet
Ramsey case and in the Nicole
Brown Simpson murder
compromised the investigation
• Proper procedure and methods
would have prevented these errors
Processing the Crime
Scene
• Important to remember that crime
labs DO NOT solve crimes
• Only investigations by police solve
crimes
• Forensics merely helps the police
to do their job
Processing the Crime
Scene
• 1st Officer’s responsibilities
– Preserve and protect the area; mark off
larger than needed
– Call for back-up
– Log all who come in/out; controls
evidence tampering
– The enter/exit area of the perpetrator is
recorded as well
– Police must ensure suspect can not
return to the scene to destroy evidence
Steps in Processing the Crime
Scene
1.Provide
medical
assistance;
save and
preserve life
Steps in Processing the Crime
Scene
2. Secure the scene
• Arrest/detain suspects
• Use crime scene tape,
barricades, cars,
officers
• Exclude ALL
unnecessary people
• Initial walkthrough:
-entry & exit?
-overview of scene
-any specialists
needed?
Saferstein video: Processing Keep
a crimehands
scenein pockets!
Steps in Processing the Crime
Scene
3. Document the scene
•
Limited time available to work a crime
scene
»
Three methods of crime-scene
recording:
1. Photography
2. Sketches
3. Notes
Forensic Photographers
• Important: Scene must be unaltered
- if changed, photos could be
inadmissible as evidence
• Photos are taken of entire crime scene,
including surrounding areas; enter and
exit areas taken at various angles;
adjacent rooms
• Bodies are also heavily photographed in
relation to where they are in the scene
Forensic Photographers
• As physical evidence surfaces,
they are photographed; often with
something next to them to indicate
size (ruler or measuring tape)
• Photographers are only able to
begin taking photos once they
have been given the okay from the
crime scene manager
Forensic Photographer
• Equipment:
– 35mm and digital cameras;
corresponding film
– Standard light (flash)
– Colored filters, light beams, UV
(stains/fingerprints after treated with
superglue or DFO), violet (gunshot
residue/blood), blue and green light
(prints/fibers/urine/semen)
Forensic Photographer
• Key point about photography is that it
allows the police to reopen a crime
scene quickly, like a busy street
- all evidence has been captured on film
• They must be ready 24/7
• Extremely difficult job because reliant
on this person’s experience to get all
data
Sketches
• After the photographer is finished,
crime scene investigators make a rough
sketch of scene
• Shows the location of all objects
• Objects are located from two fixed
points in the room like walls or a
doorknob; called DATUM
• All measurements are made with a tape
measure
N
3 ft 1 in
6 ft 3 in
Measure from two fixed points
Sketches
• Often use number or letter cards
by evidence
• Finished or final sketch is
completed back at the lab using
computers and drafting materials
– Looks “finished”
– Has a legend instead of
labels
Notes
• Notes are continuously gathered at
a crime scene
• Must identify the time evidence
was found, location, description,
who and how item was packaged
• Notes can also be taken using a
tape recorder and by video; later
must all be written down
Steps to Processing the
Crime Scene
4. Identify and interview witnesses
- keep witnesses separated
- don’t want stories contaminated
Steps to Processing the
Crime Scene
5. Search the scene
• Be thorough and systematic by
following a search pattern.
ex. line, grid, spiral, quadrant
(which one is chosen depends on locale & size of area and # of officers)
• Look for details… remember to
look up too !
Read list of details to look for…
Systematic Search for
Evidence
• A thorough, systematic search of the
crime scene necessary for court
• Not necessarily done by forensic
scientists
• There are four general search patterns
1) Spiral search
2) Grid method
3) Strip or line method
4) Quadrant or zone search
Systematic Search for
Evidence
Spiral
Grid
Line/Strip
Quadrant/
Zone
Systematic Search for
Evidence
Line
Grid
Quadrant
Spiral
Steps to Processing the
Crime Scene
6. Collect and package evidence
• Wear gloves,
booties, mask,
“bunny suit” while
collecting
Note: After 30 min. you can
leave fingerprints behind
through gloves !
Collect and package evidence
• Label each item as follows:
What is it ? eg. Blue fiber
Where found ?
Who collected it ?
Collect and package evidence
• Package each item separately
and in proper packaging:
•Examples:
- Hairs/ fibers:
paper bindle
or glassine envelope
Collect and package evidence
Powders: plastic bags
Collect and package evidence
Blood, semen stains: paper bags
(prevents bacterial and fungal growth)
*dry out first
Collect and package evidence
Weapons, bullets, casings: cardboard
boxes (prevents scratches)
Collect and package evidence
Arson evidence: air tight, lined metal
containers (prevents corrosion and
evaporation of accelerants)
Collect and package evidence
Paper documents: envelopes (paper or
Tyvek)
Collect and package evidence
Glass evidence: plastic vials
(prevents scratches)
Collect and package
evidence
• A hand-held vacuum with a special filter
can be used to collect trace evidence
• Crime scene evidence is extended into
the autopsy room:
– victim’s clothing; fingernail scrapings; head
and pubic hairs; blood; vaginal, anal and
oral swabs; recovered bullets from the
body; hand swabs from shooting victims
Evidence Collection Kit
Steps to Processing the
Crime Scene
7. Maintain Chain of Custody
• Documentation of the
movement of evidence
from collection until
case conclusion.
• Crucial to maintaining
integrity of evidence.
The Top Ten Ways to
Botch an Investigation
Go to the list