CRIME SCENE CONTROL

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Crime Scenes
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WHAT IS A CRIME?

• A crime is the commission or omission of any act,
  which is prohibited or required by the penal code
  of an organized political state, to which some
  punishment or sanction is attached.
• Classifications
• Felony
• Punishable by death or imprisonment for more than
  one year in a state prison (ex murder, rape,
  terrorism, burglary, treason)
• Misdemeanor
• Punishable by fine and/or imprisonment for up to
  one year in a local or county jail (ex petty
  theft, disorderly conduct, public intoxication,
  simple assault, vandalism)
• Infraction or Violation
• Minor offenses punishable by a fine only (ex
  jaywalking, minor traffic violations, littering,
  disturbing the peace)

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The Six Ss of Crime-Scene Investigation

• A lead investigator/first responder starts the
  process of evaluating the area.
• Securing the scene
• Protect the area within which the crime has
  occurred
• Separating the witnesses
• This avoids witness collusion
• Scanning the scene
• primary vs. secondary crime scenes
• Seeing the scene
• Photograph and triangulate
• Sketching the scene
• Rough sketch of all important objects/evidence
• Searching for evidence
• In a grid, linear, quadrant, or spiral pattern

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Locards Exchange Principle

• With contact between two items, there will always
  be a transfer of material. The longer or more
  intense the contact, the greater the amount of
  trace evidence present.
• Wherever he steps, whatever he touches, whatever
  he leaves, even unconsciously, will serve as a
  silent witness against him. Not only his
  fingerprints or his footprints, but his hair, the
  fibers from his clothes, the glass he breaks, the
  tool mark he leaves, the paint he scratches, the
  blood or semen he deposits or collects. All of
  these and more, bear mute witness against him.
  This is evidence that does not forget. It is not
  confused by the excitement of the moment. It is
  not absent because human witnesses are. It is
  factual evidence. Physical evidence cannot be
  wrong, it cannot perjure itself, it cannot be
  wholly absent. Only human failure to find it,
  study and understand it, can diminish its value.

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Crime Scene The Beginning

• Forensic science begins at the crime scene
• Every forensic investigator has to recognize
  physical evidence and properly preserve it for
  laboratory examination
• No amount of sophisticated laboratory
  instrumentation or technical expertise can
  salvage the situation if physical evidence is not
  collected properly
• Crime laboratories run on physical evidence
• Physical evidence encompasses any and all objects
  that can establish that a crime has been
  committed or can provide a link between a crime
  and its victim or a crime and its perpetrator.
• But if physical evidence is to be used
  effectively for aiding the investigator, its
  presence first must be recognized at the crime
  scene.

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Types of Physical Evidence

• Blood, semen, and saliva
• Documents
• Drugs
• Explosives
• Fibers
• Fingerprints
• Firearms and ammunition
• Glass
• Hair
• Impressions
• Organs and physiological fluids

• Paint
• Petroleum products
• Plastic bags
• Plastic, rubber, and other polymers
• Powder residues
• Soil and minerals
• Tool marks
• Vehicle lights
• Wood and other vegetative matter

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Categories of Evidence

• Class Evidence
• Material that connects an individual or a thing
  to a certain group
• Individual Evidence
• Evidence that identifies a particular person or
  thing
• Trace evidence
• Small or microscopic evidence, or evidence in
  limited amounts
• Direct Evidence
• Evidence that provides direct factual information
  in a trial
• Circumstantial Evidence
• Indirect evidence used to imply a fact
  incriminate a person
• Exculpatory Evidence
• Helps to prove that an accused is not guilty

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Crossing Over

• Crossing over the line from class to individual
  does not end the discussion.
• How many striations are necessary to
  individualize a mark to a single tool and no
  other?
• How many color layers individualize a paint chip
  to a single car?
• How many ridge characteristics individualize a
  fingerprint?
• How many handwriting characteristics tie a person
  to a signature?
• These are all questions that defy simple answers
  and are the basis of arguments.

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Evidence Recovery

• 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 and
  location relative to the entire scene.
• After these overviews are taken, close-ups should
  be taken to record the details of the object
  itself.
• When the size of an item is of significance, a
  ruler or other measuring scale may be inserted
  near the object and included in the photograph as
  a point of reference.

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Notes

• Note taking must be a constant activity
  throughout the processing of the crime scene.
• The notes must identify
• the time an item of physical evidence was
  discovered
• by whom it was discovered
• how and by whom it was packaged and marked
• the disposition of the item after it was
  collected
• The note-taker has to keep in mind that this
  written record may be the only source of
  information for refreshing ones memory.

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Sketches

• Rough Sketch A draft representation of all
  essential information and measurements at a crime
  scene. This sketch is drawn at the crime scene.
  It shows all recovered items of physical
  evidence, as well as other important features of
  the crime scene
• Finished Sketch A precise rendering of the crime
  scene, usually drawn to scale. This type is not
  normally completed at the crime scene
• Unlike the rough sketch, the finished sketch is
  drawn with care and concern for aesthetic
  appearance

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Rough sketch vs. Finished sketch
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Crime Scene Search Patterns

1. Spiral
2. Strip/Line
3. Grid
4. Zone/Quadrant
5. Pie/Wheel

• The search for physical evidence at a crime scene
  must be thorough and systematic.
• The search pattern selected will normally depend
  on the size and locale of the scene and the
  number of collectors participating in the search.
• Physical evidence can be anything from massive
  objects to microscopic traces
• There area a variety of crime scene search
  patterns based upon the type and size of the
  crime scene.

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Evidence Recovery Log

• The evidence recovery log is an important
  document which records all pieces of physical
  evidence found at a crime scene. This is critical
  if the case is to be successfully prosecuted
  later.

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The Search continued

• 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, in addition to more discernible items.
• The search for physical evidence must extend
  beyond the crime scene to the autopsy room
• The medical examiner or coroner will examine the
  victim to establish a cause and manner of death
• Tissues and organs will be retained for
  pathological and toxicological examination
• At the same time, arrangements must be made
  between the examiner and investigator to secure a
  variety of items that may be obtainable from the
  body for laboratory examination.

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Beyond the Crime Scene

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

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Packaging Evidence

• Each different 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.
• Each piece of evidence should be packaged
  properly, sealed in an evidence bag, with the
  collectors signature along the taped edge.
• If bag is opened, cut along non-taped edge and
  reseal and sign when finished.

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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, whether it is soil,
  blood, glass, hair, fibers, and so on, often
  requires comparison with a known
  standard/reference sample.
• Although most investigators have little
  difficulty recognizing and collecting relevant
  crime scene evidence, few seem aware of the
  necessity and importance of providing the crime
  lab with a thorough sampling of
  standard/reference materials.

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Evidence in a Court of Law

• Chain of Custody A list of all persons who came
  into possession of an item of evidence.
• The chain of custody, if not carefully managed,
  not only increases the risk of contamination, but
  it also can introduce a reasonable doubt
• Frye Standard (1923)
• Is the scientific theory/method generally
  accepted in the scientific community?
• Has the technique been applied correctly?
• Daubert vs. Merril Dow (1993)
• Has the scientific theory/technique been tested?
• Has the scientific theory/technique been subject
  to peer review or publication?
• Do standards/controls exist, and are they
  maintained?
• What are the known or potential error rates of
  the theory/technique when applied?

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Evidence in a Court of Law-Admissibility

• Relevance does it relate to this particular case
• Material evidence must relate to the case at
  hand. Previous criminal records are not
  material, can be prejudicial and are therefore
  inadmissible
• Probativeness evidence must prove something in
  relation to the case.
• Prejudice anything that unduly affects the
  opinion for or against an accused
• Statutory Constraints also called privileged
  information, or information told to a person who
  cannot reveal it (clergy, lawyers, etc)
• Hearsay a statement made outside of court by a
  person not under oath when the statement was made

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Evidence in a Court of Law Constitutional
Constraints

• 4th Amendment
• Protects individuals from illegal search and
  seizure. Evidence obtained without a warrant,
  without probably cause, and not listed on a
  warrant is inadmissible regardless of relevance.
  (except in the existence of emergency
  circumstances, need to prevent immediate
  loss/destruction of evidence, consent of the
  parties involved)
• 5th Amendment
• Protects individuals from double jeopardy and
  from being tried for a capital crime unless
  indicted by a grand jury
• 6th Amendment
• An individuals right to a speedy and public trial
  by an impartial jury
• 7th Amendment
• Common law right to a trial by jury
• 8th Amendment
• Protection from excessive bail, fines, and cruel
  and unusual punishment

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Evidence in a Court of Law Expert Witness

• Forensic evidence relies on the testimony of
  expert witnesses
• A person with the appropriate training and
  experience necessary to give valuable information
  pertaining to evidence used in the trial
• A non-expert is called a lay witness
• An expert must be qualified as an expert every
  time he/she testifies in court
• An expert is permitted to offer opinions, whereas
  a lay witness generally cannot

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Evidence in a Court of Law

• Innocent until proven guilty
• Reasonable Doubt the prosecution has the burden
  of proof. The defense has the responsibility to
  either exonerate the accused, or at least
  introduce a reasonable doubt.
• The defense must provide a spirited defense,
  regardless of guilt or innocence of the accused
  (or a mistrial can be called)
• Discovery Motion the defense is required access
  to the witness list, as well as other evidence,
  so that it may carry out its own evaluation of
  the evidence

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Case Studies

• O.J. Simpson-1994
• Evidence not handled well, leading to
  suggestions it was compromised by dishonest
  criminalists and police.

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Outside Nicole Brown-Simpsons home
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JonBenet Patricia Ramsey (1990-1996)
JonBenet Ramsey Crime scene wasnt secured and
family friends and father found body,
contaminating the scene