FORENSIC SCIENCE

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Observation Skills

• Are there cars parked on the sides of the
  road?
• What color is the pickup truck driving in the
  road?
• Any minivans around?
• What does the blue sign say?
• What's the speed limit?
• Are there any pedestrians on the road?

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Chapter 3 THE CRIME SCENE

• Oh, how simple it would all have been had I
  been here before they came like a herd of buffalo
  and wallowed all over it.
• A. Conan Doyle, in The Boscombe Valley Mystery,
  1892

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CRIME SCENE

• Students will learn
• The steps to take when processing a crime scene.
• The type of evidence that determines what
  packaging should be used.
• Why the chain of custody must be preserved.
• Students will be able to
• Isolate, record, and search for evidence at a
  mock crime scene.
• Collect and package evidence at a mock crime
  scene using to proper forensic procedures.

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Steps to PROCESS ACRIME SCENE

• Isolate and secure the scene
• Document the scene
• Search for evidence
• Collect and package evidence, maintaining the
  chain of custody
• Submit evidence to the crime lab

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FIRST OFFICERON THE SCENE

• A Assess the crime scene and assist those hurt
• D Detain the witness
• A Arrest the perpetrator
• P Protect the crime scene
• T Take notes

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CRIME SCENE SURVEY

• Walk-throughperformed by the crime scene
  investigator, the first officer and sometimes the
  lead detective
• Purpose
• Mentally prepare a reconstruction theory
• Note any transient or conditional evidence that
  could change over time.
• Note weather conditions
• Note points of entry or exit, as well as paths of
  travel within the crime scene
• Record initial observations of who, what, where,
  when, and how

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DOCUMENTATION

• Notesnote taking is a continuous activity,
  includes
• - date and time
• - detailed, written description of the crime
  scene
• - weather and environmental conditions
• - location of the evidence, time discovered
• - names of all people involved

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Documentation

• Sketchesaccurate dimensions of the scene showing
  the location of all relevant objects sketch
  should reflect all recovered items of physical
  evidence

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Rough Sketch
Definition a draft representation of all
essential information and measurements at a crime
scene. The sketch is drawn at the crime scene.
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Finished Sketch

• Definition a precise rendering of the crime
  scene, drawn to scale.

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CRIME SCENE SKETCH
Date August 14, 2005 Criminalist Ann
Wilson Time 1135 am Location 4358
Rockledge Dr, St. Louis, Mo.
N
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PROCESSING ACRIME SCENE

• Do you have what it takes?

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Lab Assignment
Lab Handout Be Careful and follow all
instructions given NO TALKING during lab lets
see how well you can process a crime scene
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CRIME SCENE INVESTIGATION

• Based on the scientific method and the Locard
  Exchange Principle, logic and forensic techniques
• Involves
• Recognitionscene survey, documentation,
  collection
• Identificationcomparison testing
• Individualizationevaluation and interpretation
• Reconstructionreporting and presenting

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SEARCH METHODS

• Line or strip methodbest in large, outdoor
  scenes
• Grid methodbasically a double-line search
  effective, but time-consuming
• Zone methodmost effective in houses or
  buildings teams are assigned small zones for
  searching
• Wheel or ray methodbest on small, circular crime
  scenes
• Spiral methodmay move inward or outward best
  used where there are no physical barriers

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COLLECTING AND PACKAGING EVIDENCE

• One individual should be designated as the
  evidence collector to ensure that the evidence is
  collected, packaged, marked, sealed, and
  preserved in a consistent manner
• Each item must be placed in a separate container,
  sealed, and labeled
• Most fragile is collected and packaged first
• Different types of evidence require specific or
  special collection and packaging techniques
• The body is the property of the coroner or
  medical examiner. The collection of evidence on
  the body is done by that department

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PACKAGING

• Most items should be packaged in a primary
  container and then placed inside a secondary one.
  These are then placed inside other containers
  such as paper bags, plastic bags, canisters,
  packets and envelopes depending on the type and
  size of the evidence.

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CHAIN OF CUSTODY

• There must be a written record of all people who
  have had possession of an item of evidence.
• The evidence container must be marked for
  identification
• The collectors initials should be placed on the
  seal
• If evidence is turned over to another person, the
  transfer must be recorded.