Forensic Science The Crime Scene Introduction to Crime Scene

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Forensic Science

• The Crime Scene

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Introduction to Crime Scene Investigation

• The purpose of crime scene investigation is to
  help establish what happened (crime scene
  reconstruction) and to identify the responsible
  person.
• carefully documenting the conditions at a crime
  scene and recognizing all relevant physical
  evidence.
• The ability to recognize and properly collect
  physical evidence is oftentimes critical to both
  solving and prosecuting violent crimes.
• It is important to determine the full extent of a
  crime scene. A crime scene is not merely the
  immediate area where a body is located or where
  an assailant concentrated his activities but can
  also encompass a vehicle and access/escape
  routes.
• . In the majority of cases, the law enforcement
  officer who protects and searches a crime scene
  plays a critical role in determining whether
  physical evidence will be used in solving or
  prosecuting violent crimes

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The Crime Scene

• A place where a crime has taken place.
• A starting point for a criminal investigation.
• There is no "crime scene exception" to the Fourth
  Amendment.
• That is, once the emergency is over, and police
  have secured the scene, then the police must
  comply with Fourth Amendment requirements. 
• If the scene is a protected area such as a house
  or private part of a business, then a search
  warrant or consent must be obtained. 
• Of course officers can secure and protect the
  scene until these requirements are met (Flippo v.
  West Virginia).

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Processing the Crime Scene

• There are 7 steps to processing a crime scene
• Secure and Isolate the Crime Scene
• Record the Scene Photograph, Sketch, Take Notes
• Conduct a Systematic Search For Evidence
• Collect and Package Evidence
• Maintain Chain of Custody
• Obtain Controls
• Submit Evidence to the Laboratory

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Law Enforcement Personnel on the scene

• In order for physical evidence to be analyzed and
  to tell its part of the story, it must first be
  properly collected.
• In order for the proper collection to take place,
  the crime scene, must be properly secured,
  protected, and preserved.
• This scene security, protection, and preservation
  is the responsibility of any and all law
  enforcement personnel who come in contact with
  the scene, the suspect, and/or the victim.

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Crime Scene Investigation Team

• Team Leader
• Photographer and Photographic Log Recorder
• Sketch Preparer
• Evidence Recorder/Evidence Recovery Personnel
• Specialists

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Team Leader

• Assume control - ensure safety of personnel and
  security at scene, use of appropriate protective
  equipment to avoid any health hazard from blood
  or any other human body fluid.
• Conduct initial walk-through to make a
  preliminary survey, evaluate potential evidence,
  and prepare a narrative description.
• Determine search patterns, and make appropriate
  assignments for team members.
• Designate command post location and ensure
  exchange of information between search and
  investigative personnel.
• Coordinate and cooperate with other law
  enforcement agencies
• Ensure that sufficient supplies and equipment are
  available
• Control access to the scene and designate an
  individual to log everyone into the scene.
• Continuously reevaluate efficiency of search
  during entire course of operation.
• Release the scene after a final survey and
  inventory of the evidence has been done.

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Crime Scene Search Patterns

• The purpose of a search is to locate, identify,
  and collect any tangible material which may be
  associated with a suspect and/or victim from the
  crime scene and/or the crime.
• There are standard search patterns used at a
  crime scene, especially when the scene is very
  large. These patterns include spiral, grid,
  strip or line, and quadrant or zone search
• Important things to do during a search
• Search from the general to the specific for
  evidence.
• Be alert for all evidence.
• Search entrances and exits.
• Discuss the search with all personnel.

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Recording the Crime Scene

• Documentation includes transient details such as
  lighting (on/off), drapes (open/closed), weather,
  or furniture moved by medical teams.
• The scope extends to possible arguments which
  might be made in this case (suicide/self defense)
  and documenting conditions supporting or refuting
  these arguments.
• Important to recognize what should be present at
  a scene but is not (victim's vehicle/wallet) and
  objects which appear to be out of place (ski
  mask) and might have been left by the assailant.

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Photographer/Photographic Recorder

• Photograph entire area before it is entered.
• Photograph victims, crowd, and vehicles.
• Photograph entire scene with overall, medium and
  close-up coverage, using measurement scale when
  appropriate.
• Photograph major evidence items before they are
  moved
• Photograph all latent fingerprints and other
  impression evidence before lifting and casting
  are accomplished.
• Prepare photographic log and sketch.

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Photographing the Crime Scene

• Film is cheap you can never take too many
  pictures.  Utilize a flash if necessary.
• Move evidence for better photographs only after
  the "as is" photograph has been taken and is
  necessary for additional identification.

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Sketch Preparer

• Diagram immediate area of scene and orient
  diagram with sketch.
• Show major items of evidence on sketch.
• Designate and label areas to be searched and
  advise team leader and all other search members
  of designated search areas.
• Obtain assistance for taking measurements and
  double check measurements.
• Ensure necessary administrative information, such
  as scale disclaimer (not drawn to scale), is
  recorded on sketch.

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Sketching the Crime Scene

• Documentation of physical evidence locations, as
  well as measurements showing pertinent size and
  distance relationships in the crime scene area.

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Evidence Collector/Custodian

• Have significant evidence photographed before
  collection.
• Describe evidence and its location on appropriate
  bag or envelope.
• Sign and date evidence container/maintain chain
  of custody.
• Appropriately collect and package evidence to
  maximize evidence integrity.
• Maintain evidence log.
• Use appropriate protective equipment (gloves) and
  methods when dealing with potentially infective
  evidence (blood).

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Collecting Physical Evidence

• Any collected evidence should have its location
  and condition documented before it is removed
• Evidence should be collected in appropriate
  containers, wearing gloves
• Containers/envelopes should be sealed with
  tamper-proof tape
• Seals should be signed
• Chain of Custody must be maintained

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Information On Evidence Packaging

• The following information should be included on
  evidence packaging
• Location of crime scene
• Location of evidence at scene and time of
  collection
• Personnel who collected the evidence
• Condition of item at time of collection
• Chain of Custody log

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Specialists

• It is sometimes necessary to bring in expertise
  from an outside agency.
• The field of forensic science is so broad today
  that no agency will have every form of specialty
  service available from among its ranks.
• Typically, specialists are brought in from
  industry, the academic community, private
  scientific laboratories, and similar concerns.
• Some items to consider when dealing with outside
  specialists
• The competence and reliability of the specialist.
• The ability of the specialist to work at a scene
  within law enforcement guidelines.
• The role of the specialist in presenting expert
  testimony in court.

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Obtaining Controls from the Crime Scene

• Controls are physical evidence whose origins are
  known, such as carpet fibers from a suspects
  home, that can be compared to crime scene
  evidence.
• The crime lab must have a thorough sample of
  control materials for comparison.

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Submitting Evidence to the Crime Lab

• Evidence can be submitted to the crime laboratory
  by a crime scene investigator personally or via
  the mail
• Chain of Custody must be maintained at all times
• Many labs require specific documentation before
  they will process evidence
• Evidence evaluated by the lab may take a long
  time to process, or be held due to back log.