Investigating the Crime Scene

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Investigating the Crime Scene
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Chapter Objectives

• Students should gain an understanding of
• The steps taken to secure a crime scene
• Documentation of the crime scene
• Ways to systematically search the crime scene
• Methods for collecting, preserving, identifying,
  packaging, and transporting evidence
• The chain of custody
• The Fourth Amendment and its application to the
  search and seizure of evidence

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Introduction

• Collection and preservation of evidence are
  essential for successful criminal investigation.
• Failure to assure proper collection and
  preservation can jeopardize the investigation.
• Accurate records are needed of the actions taken
  by investigators.
• Physical evidence is usually collected by the
  police or civilian crime scene technician it
  includes any and all relevant materials or
  objects associated with the crime scene, victim,
  suspect, or witness.

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Securing the Crime Scene

• First responder
• Offer assistance to injured persons
• May exclude nonessential persons from the crime
  scene
• Later responders
• Are responsible for security of crime scene
• Limit access All who enter have potential for
  contamination

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Securing the Crime Scene

• The first responder should
• Set initial boundary larger than the scene
• Locate physical evidence for later
  identification, collection, and submission
• Create single path in and out of scene
• Document all actions and observations
• State of scene and all existing conditions
• Personal information
• Actions and statements of persons entering and
  exiting
• Items moved and who moved them

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The Preliminary Exam

• A lead investigator will get a report from the
  first responder then start the process of
  evaluating the area before collecting evidence.
• The investigator then proceeds with an initial
  walk-through of the scene to gain an overview of
  the situation and develop a strategy for the
  systematic examination and documentation of the
  entire crime scene.

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The Search

• The search for physical evidence at a crime scene
  must be thorough and systematic using a spiral,
  grid. line or zone search.
• The search pattern selected will normally depend
  on the size and locale of the scene and the
  number of evidence collectors.
• Physical evidence can be anything from massive
  objects to microscopic traces.

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The Search

• Often, many items of evidence are clearly visible
  but others may be detected only through
  examination at the crime laboratory.
• For this reason, it is important to collect
  possible carriers of trace evidence, such as
  clothing, vacuum sweepings, and fingernail
  scrapings, etc.
• Investigators wear gloves to prevent their
  contamination of the scene.

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Systematic Search for Evidence
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Systematic Search for Evidence

• Methodically search for less obvious pieces of
  evidence
• Search patterns
• Spiral no physical boundaries
• Grid large outdoor crime scene
• Strip outdoor crime scene where coordinator
  organizes many searchers
• Zone indoor crime scene where different teams
  are assigned small areas
• Wheel circular crime scenes

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Systematic Search for Evidence

• Search suspected points of ingress and egress
• Collect evidence that might degrade first
• Search outside scenes in daylight if possible
• Recognition of physical evidence
• First step in processing is to recognize obvious
  pieces of physical evidence
• Ability to recognize what is and is not evidence
  is learned through experience
• Many departments employ specialized evidence
  retrieval technicians
• The nature of the crime determines the type of
  evidence sought

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Systematic Search for Evidence
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What Evidence Would You Collect?
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Documenting the Scene

• Investigators may have only a limited amount of
  time to work a crime scene.
• Photographs, notes and diagrams document the
  condition of the crime scene and to delineate the
  location of physical evidence.
• Photographs, notes and diagrams prove useful
  during the subsequent investigation AND are also
  required for presentation at a trial often months
  or years later.

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Documenting the Scene

• Documenting is the most important and
  time-consuming activity at a crime scene because
• Maintaining chain of custody proves nothing was
  altered.
• It demonstrates who discovered an item, when it
  was discovered, and the items appearance,
  control, movement.
• It helps the analyst understand how the evidence
  relates to the overall scene.
• It is used to present the case in court.

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Documenting the Scene Evidence

• Note taking
• Document core of crime scene and all physical
  evidence
• Make notes in ink, in a bound notebook, with
  pages numbered sequentially
• Do not erase errors cross them out with pen
• Make notations in chronological order
• This is needed since the notes may become
  evidence used in court

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Documenting the Evidence

• Note taking
• Evidence is documented in notes by describing
• Type and condition of evidence
• Time of discovery
• Name of discoverer
• Placement, collection, packaging, labeling
• Photographs must also be documented
• Audio or video recordings may be used, but later
  must be transcribed or summarized in a report

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Documenting the Scene Evidence

• Photography
• Take photos without disturbing elements of the
  scene
• Take a systematic series of photos to record all
  possible views of the crime scene
• Photograph as thoroughly as possible
• Use a 35-mm single-lens reflex camera
• Retain the original digital images

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Photography

• The most important prerequisite for photographing
  a crime scene is for it to be in an unaltered
  condition.
• Unless there are injured parties involved,
  objects must not be moved until they have been
  photographed from all necessary angles.
• As items of physical evidence are discovered,
  they are photographed to show their position,
  size and location relative to the entire scene.

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Photography
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Photography

• After overviews are taken, close-ups should be
  taken to record the details of the object itself.
  
• A ruler or other measuring scale may be placed
  near the object and included in the photograph.
• Once photographs are taken, the crime-scene
  investigator will sketch the scene.
• A photo log of the crime scene must also be
  created.

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Photography

• Items included in the photo log
• Date and time
• Camera settings
• Film roll number and exposure number
• File name and exposure number
• Type of shot
• Distance to the subject
• Brief description

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Sketches

• Rough SketchA representation of all essential
  information, evidence and measurements at a
  crime scene drawn at the crime scene.

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Documenting the Scene Evidence

• Sketching
• Accurately record distances between objects
• Make rough sketches not drawn to scale, but with
  adequate information for later finishing
• Sketch the scene from an overhead view
• Must establish two fixed points that are
  permanent objects
• Recognize that a computer professional will
  prepare finished sketches later using CAD
  software

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Sketches
Finished SketchA precise rendering of the crime
scene, usually drawn to scale. This type is not
normally completed at the crime scene.
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Sketches

• Items included in a sketch
• Case identifier
• Date, time, location
• Weather and lighting conditions
• Name of the sketch
• Identity and assignments of personnel
• Dimensions and layout
• Measurements and positioning
• Key or legend
• Orientation
• Scale

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How to Identify Evidence Positions
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Sketches

• Three techniques for determination of position of
  evidence within the crime scene are
• Triangulation measures location of the evidence
  from fixed points
• Baseline draws a line between the fixed points
  and measures the distance to the evidence at a
  right angle from this line
• Polar coordinate method uses a transit or
  compass to measure the angle from the north and
  the distance to the evidence

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Documenting the Scene Evidence

• Videography
• May be used to complement still photography
• Is the best way to document the overall view of
  the scene
• Allows forensic scientists to understand the
  scene at a later time
• Record locations of evidence in still photos
• Record running audio narrative

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Beyond The Crime Scene

• The search for physical evidence must continue to
  the autopsy room of a deceased victim.
• The medical examiner or coroner will carefully
  examine the victim to establish a cause and
  manner of death.
• Tissues and organs will be retained for
  pathological and toxicological examination.
• Also they will provide any physical evidence from
  the body of the victim.

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Beyond The Crime Scene

• The following are often collected and sent to the
  forensic laboratory
• Victims clothing
• Fingernail scrapings
• Head and pubic hairs
• Blood (for DNA typing purposes)
• Vaginal, anal, and oral swabs (in sex related
  crimes)
• Recovered bullets from the body
• Hand swabs from shooting victims (for gunshot
  residue analysis)

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Collection of Evidence

• Once documented, evidence must be collected,
  preserved, inventoried, and packaged in
  preparation for submission to the crime lab.
• Known samples come from relevant persons and are
  used for comparison.

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Collection of Evidence

• Impression evidence
• Developed or enhanced by use of specialized
  photographic techniques or chemical developers
• Biological evidence
• Enhanced/developed by chemical means
• Collected with sterile swabs
• Firearms and ammunition
• Located by sight
• Must be rendered safe
• Store in paper envelopes, bags, or boxes

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Collection of Evidence

• Arson and bomb evidence
• Locate by sight and smell
• Place carpet, wood, and absorbent materials in
  clean paint cans and seal lid
• Place flammable liquids in glass bottle with
  tight-fitting lid
• Chemicals and controlled substances
• Locate by visual observation
• Place liquids and solids in screw cap jar or vial

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Collection of Evidence

• Trace evidence
• May be extremely small or microscopic
• Collect by forceps, tweezers, scraping, taping,
  or vacuuming
• Document and collect questioned and known samples
• Work in conjunction with medical examiner for
  homicide evidence collection

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Obtaining Reference Samples

• Standard/Reference SamplePhysical evidence whose
  origin is known, such as blood or hair from a
  suspect, that can be compared to crime-scene
  evidence.
• The examination of evidence often requires
  comparison with a known standard/reference
  sample.
• Few investigators seem aware of the importance of
  providing the crime lab with a sampling of
  standard/reference materials.

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Packaging Evidence

• Each item or similar items collected at different
  locations must be placed in separate containers.
• Packaging evidence separately prevents damage
  through contact and prevents cross-contamination.
• The well-prepared evidence collector will have a
  large assortment of packaging materials and tools
  ready to encounter any type of situation.

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Packaging Evidence

• Take entire piece of evidence as it is found at
  the scene, if possible.
• Package must preserve and protect evidence.
• Wet blood should dry first and then be scraped or
  wet blood can be collected on a swab.
• If bloodstained materials are stored in airtight
  containers, the accumulation of moisture may
  encourage the growth of mold, which can destroy
  the evidential value of blood.

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Packaging Evidence

• Unbreakable plastic pill bottles with pressure
  lids are excellent containers for hairs, glass,
  fibers, and other kinds of trace evidence.
• Manila envelopes, screw-cap glass vials, or
  cardboard pillboxes are also good containers.
• Ordinary mailing envelopes should not be used
  because powders will leak out of their corners.

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Packaging Evidence
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What evidence could go in each type of container?
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Submitting Evidence to The Lab

• Evidence should be sent directly to the lab to
  preserve the chain of custody
• It may be submitted to the crime lab in person or
  via mail.
• A Federal Firearms License required for postal
  mailing of firearms.
• Chemicals, radiological agents, and explosives
  may be transported via UPS or FedEx.
• Each item must be packaged separately.
• Once at the lab, the evidence is placed in
  constantly guarded evidence storage areas.

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Chain of Custody
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Chain of Custody

• In court, all evidence will be subject to
  questions about chain of custody.
• The chain starts with the evidences original
  discoverer.
• The chain is broken if movements are not
  documented that may result in evidence being
  excluded in court.
• Preserve the chain of custody by making sure that
  investigator notes completely document everything
  that happens to each piece of evidence at the
  scene and once it is in the lab.

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Evidence and the Fourth Amendment

• Evidence is most often excluded due to Fourth
  Amendment violations.
• Officers must present an affidavit of probable
  cause that criminal activity is taking place at a
  particular location to receive a search warrant.
• Contraband, fruits and instrumentalities of the
  crime, evidentiary items, voice and handwriting
  samples, and conversations can all be obtained
  via warrants.

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Evidence and the Fourth Amendment

• Exceptions to the Fourth Amendment
• Border searches customs searches at the border
  do not require a warrant
• Consent searches persons can voluntarily submit
  to a search
• Search incident to arrest persons and the area
  under immediate control can be searched during a
  lawful arrest
• Plain view doctrine officers can seize
  contraband and evidence that they can see from
  legal vantage point

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Evidence and the Fourth Amendment

• Exceptions to the Fourth Amendment
• Emergency exceptions officers can enter premises
  without a warrant if they have reasonable
  suspicion that an injured person is inside
• Open fields no expectation of privacy
• Stop and frisk officer may pat down a suspicious
  person who may be armed and dangerous
• Vehicle inventories may need to search the
  vehicle immediately if the driver or other
  occupant is arrested

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Evidence and the Fourth Amendment

• Mincey v. Arizona (1978)
• Police conducted an undercover raid of a
  suspected drug house.
• An officer and three suspects were shot.
• The premises were searched extensively over 4
  days without a warrant.
• The court overturned the conviction The offense
  did not merit a warrantless search because the
  evidence would be not lost while a warrant was
  obtained.

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Evidence and the Fourth Amendment

• Michigan v. Tyler (1978)
• It involved a fire at a furniture store.
• Investigators conducted several searches,
  including some well after the fire was out.
• The convictions were overturned The later
  warrantless entries were not part of the initial
  emergency circumstances.
• Officers must obtain a search warrant before they
  conduct a careful, detailed examination of a
  crime scene.