Transcript The Crime Scene - Bio-Guru

The Crime Scene
Chapter 2
Processing The Crime Scene
Forensic Science begins at the crime scene
- Physical Evidence: Any object (natural or
manufactured) that can establish that a
crime has been committed or can provide
a link between a crime and its victim or
between a crime and its perpetrator.
Fundamental Practices at a Crime Scene
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Secure and Isolate Crime Scene
Record Crime Scene
Photograph Crime Scene
Sketch Crime Scene
Maintain excellent Notes
Conduct Systematic Search for Evidence
Collect and Package Physical Evidence
Maintain Chain of Custody
Obtain Standard/Reference Samples
Submit Evidence to Library
Maintain Safety at Crime Scene
Secure and Isolate Crime Scene
• Responsibility of the first officer arriving on the
scene.
• Medical assistance must be given to anyone in
need
• Scene must be preserved and protected
because every person entering scene is a
potential destroyer of evidence (intentionally or
accidentally)
– No unauthorized personnel (including spectators,
unauthorized police officers and media) on scene
– Ropes, tape, barricades used to secure scene
– Record maintained of all people entering and leaving
crime scene
Record Crime Scene
Once the crime scene is secure, the lead
investigator evaluates the area. There is a very
limited amount of time to process scene before it
gets disrupted by various personnel
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Boundaries of crime scene determined
Initial walk-through conducted
Strategy developed to process scene
Photograph and/or sketch scene
Take detailed notes
Photograph Crime Scene
• Photographs must be taken without
altering the scene or moving objects
(unless there are injured people that need
medical attention).
• If anything gets moved, photos may not be
admissible in court as evidence.
• Detailed notes should be taken to
override this issue.
Photography cont’d.
• Crime scene must be photographed thoroughly (from
various angles)
• All adjacent areas as well
• All points of entry and exit
• If scene includes body, pictures of the position and
location relative to entire scene must be taken
• Close-ups of injuries, weapons
• Once body is removed, the surface under body must be
photographed
• Each piece of physical evidence must be photographed
in its original location next to a ruler or other measuring
device AND a number I.D. card
• Video recorders are also being used these days, but
have not replaced still photographs
Sketch Crime Scene
Once photographs are taken, the crime-scene
investigator will sketch the scene (a rough
sketch, since there is no time to make a polished
one)
A rough sketch employs geometric shapes and
letters and numbers.
A finished sketch is created with mush more care
and detail. Computer aided drafting (CAD) can
be employed to do this.
Rough Sketch
Finished Sketch – Hand Drawn
Finished Sketch (CAD)
Maintain Excellent Notes
• Must be a constant activity
• Must include a written description of scene
and location of all objects of physical
evidence
• Tape-recorded notes can be more
advantageous – faster. But at some point
in time the tapes must be transcribed into
written/typed notes.
Conduct Systematic Search for Evidence
• Physical evidence may be large or microscopic,
therefore searches have to be conducted with extreme
care and have to be thorough.
• Hap-hazard searches will lead to important clues being
missed or lost.
• Systematic searches, using specific patterns are used.
• Critical areas of the scene may be vacuumed with
portable vacuum cleaners equipped with special filters
• The search for physical evidence must extend beyond
the crime scene to the autopsy room of the victim – the
medical examiner will contribute to the evidence list with
results of toxicology and pathology examinations of
various body parts, organs, tissues, etc.
Spiral Search
Grid and Zone
Also called the Quadrant Method
Parallel
Vacuum sweeper attachments
The following list of physical
evidence is collected to be sent to
the forensic laboratory:
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Victim’s clothing
Fingernail scrapings
Head and pubic hairs
Blood (For DNA typing)
Vaginal, anal, oral swabs (sex-crimes)
Bullets recovered from body
Hand swabs from shooting victims (GSR
tests)
Collect and Package Physical Evidence
• Physical evidence must be collected and
packaged correctly so it does not change from
the time it was collected to the time it is
processed by the crime lab. Changes such as
evaporation, contamination, breakage, etc.
• Each different piece of physical evidence must
be packaged separately.
• Evidence must be handled with forceps (gloved
hands only) or similar tools
Collect and Package Physical Evidence
• Plastic pill bottles, manila envelopes, glass
bottles: for storing hair, fibers, glass and
various small or “trace” evidence.
• Paper with “druggist fold”: an alternative
way to store trace evidence.
Blood-stained materials must be stored
in paper bags or manila envelopes
Blood-soaked clothing must NOT be stored in air-tight
containers because the trapped moisture may
cause the growth of mildew and mold and destroy
the blood.
All clothing in fact, must be air-dried and individually
stored in paper bags.
Charred clothing or debris on the contrary, MUST be
stored in air-tight containers so that evaporation of
volatile petroleum residues does not occur.
Maintain Chain of Custody
• A list must be maintained of all persons who came into
possession of a particular item of evidence.
• Failure to do this may will lead to serious questions
regarding the authenticity and integrity of the evidence
and it may not be admissible in court.
• Each time an evidence container is opened and closed,
it must be sealed with a label with the examiner’s name,
date and location of the item.
• If the evidence is moved to another location/lab, the date
of this transfer must also appear on the label.
• In addition, a complete record of all persons in touch with
the evidence is maintained and these persons may be
summoned to court to testify during court proceedings.
Obtain Standard/Reference Samples
• All evidence must be compared to with a
known (standard/reference) sample
• For example, blood-stained evidence must
be accompanied by blood or buccal
samples from both the victim as well as
the suspect(s)
• Same is true with hair, fibers, soil, etc.
Submit Evidence to Library
• Can be delivered to lab by personal delivery or
mail delivery but certain materials cannot be
mailed – explosive, certain chemicals, live
ammunition, etc.
• Receiving lab must get a case history or any
such report along with the evidence.
• There should be a clear request of type of
examination for each piece of evidence –
however, an analyst may perform other tests on
the pieces of evidence if necessary (in addition
to the tests requested)
• An evidence submission form must be
completed with a list of all evidence items being
submitted for tests.
Crime-scene Safety
• All CSI have to be extremely careful due to
the increasing spread of HIV, Hepatitis
B&C, and other diseases carried in bodily
fluids.
• Inoculations against Hepatitis B are made
available to all law enforcement officials
according to OSHA (Occupational Safety
and Health Administration)
CSI Safety Guidelines:
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Double layer of latex gloves
Protective Tyvek® shoe covers
Tyvek ® or Kleengard ® coveralls or suits (liquid repellant)
Particle mask/respirator, goggles/face shield to prevent exposure to dust,
mist, body fluids, etc.
Be aware of sharp objects like broken glass, knives, needles, etc.
Use biohazard labels when collecting materials hazardous to health.
All gloves, masks, suits must be disposed of in red biohazard bags, taped
shut and sent to a proper facility for incineration.
Note-taking should be done with fresh, uncontaminated gloves to prevent
contamination of pens, pencils and notepads.
Torn or soiled protective gear must be removed immediately and replaced
with a fresh one, AFTER the individual disinfects the contaminated body
area with 10% bleach solution, antimicrobial wipes, etc.
Absolutely no eating, drinking, smoking in the crime scene or laboratory.
All non-disposable items such as cloth lab coats, etc. must be placed in
yellow bags labeled “Infectious linen” and sent to a proper facility for
laundering and disinfection.
CSI Clean-up crew
Legal Considerations at a Crime Scene
• The removal of any person or evidence from a
crime scene must be done in conformity with
Forth Amendment privileges:
– The right of the people to be secure in their persons,
houses, papers, and effects, against unreasonable
searches and seizures, shall not be violated, and no
Warrants shall issue, but upon probable cause,
supported by Oath or affirmation, and particularly
describing the place to be searched, and the persons
or things to be seized.
Warrant or no warrant
Therefore, search warrants are required. A
warrantless search can only be conducted
under the following circumstances:
1. Existence of an emergency
2. To prevent immediate loss or destruction of
evidence
3. Search of a person or property of the person
during his arrest
4. Search an seizure with the consent of the
persons involved
THE END