Presentation on theme: "Chapter 3: THE CRIME SCENE 0. Chapter 3 1 The Crime Scene Crime scene any place where evidence may be located to help explain events."— Presentation transcript:
Chapter 3: THE CRIME SCENE 0
Chapter 3 1 The Crime Scene Crime scene any place where evidence may be located to help explain events
Chapter 3 2 CRIME SCENE INVESTIGATION Based on the scientific method and the Locard Exchange Principle, logic and forensic techniques Involves: Recognition—scene survey, documentation, collection Identification—comparison testing done in the lab Individualization—evaluation and interpretation Reconstruction—reporting and presenting
Chapter 3 3 PROCESSING A CRIME SCENE 1) Isolate and secure the scene 2) Survey and document the scene 3) Search for evidence 4) Collect and package evidence, maintaining the chain of custody 5) Submit evidence to the crime lab
Chapter 3 Crime Scene Contamination First officer on the scene needs to secure the crime scene so no contamination can occur contamination to make impure, corrupt, by contact; pollute, taint (according to Webster’s) Usually results through the actions of the personnel at the scene Each time the crime scene is entered by a person, not only can the person potentially leave trace evidence behind, but they can also take evidence away from the scene 4
Chapter 3 Crime Scene Contamination The potential for evidence (or crime scene) contamination increases as the number of people entering a crime scene also increases Environmental conditions may also play a major role in the contamination of crime scene evidence %20Issues.htm %20Issues.htm 5
Chapter 3 To help prevent maximum contamination 1)Determine dimensions of crime scene and secure it Outdoor is harder to secure than indoor Use of barrier tape to do this 2)Establish a command post Limits personnel access to scene Identifies who goes in / who goes out 3)Be aware of cross contamination between equipment 6 Crime Scene Contamination
Chapter 3 7 CRIME SCENE SURVEY Walk-through—performed 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 Identify special needs within the crime scene for personnel, precautions or equipment and notify superior officers or other agencies
Chapter 3 8 CRIME SCENE DOCUMENTATION Notes—date and time, description of the location, weather and environmental conditions, description of the crime, location of the evidence relative to other key points, the names of all people involved, modifications that have occurred and other relevant information Photography—photos of scene and surroundings, mid- range to close-up photos with various angles of each piece of evidence, photos as viewed by any witnesses. Sketches—inclusion of date, time, scale, reference points, distance measurements, names of investigators, victims, suspects, and a legend (key) Videography—allows narration (non-subjective) to be included
Chapter 3 CRIME SCENE SEARCH PATTERNS 2-18 (a)Spiral (b)Strip/Line (c)Grid (d)Zone/Quadrant (e)Pie/Wheel Spiral method (a)—may move inward or outward; best used where there are no physical barriers Line or strip method (b)— best in large, outdoor scenes Grid method (c)—basically a double-line search; effective, but time-consuming Zone method (d)—most effective in houses or buildings; teams are assigned small zones for searching Wheel or pie method (e)— best on small, circular crime scenes
Chapter 3 10 CRIME SCENE SKETCH N
Chapter 3 Drawing to Scale 11
Chapter 3 12 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
Chapter 3 13 THE MEDICAL EXAMINER AND THE CORONER A medical examiner is a medical doctor, usually a pathologist and is appointed by the governing body of the area. A coroner is an elected official who usually has no special medical training.
Chapter 3 14 MEDICAL EXAMINER’S RESPONSIBILITIES Identify the deceased Establish the time and date of death Determine a medical cause of death—the injury or disease that resulted in the person dying Determine the manner of death—the physiological reason that the person died Classify the manner of death Natural Accidental Suicide Homicide Undetermined Notify the next of kin
Chapter 3 15 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 collector’s initials should be placed on the seal If evidence is turned over to another person, the transfer must be recorded.
Chapter 3 Emotional Hazards Can occur at any incident but is especially possible at violent crime scenes and mass casualty incidents Psychologists are often called in to deal with these incidents (CISM) Symptoms may include substance abuse, anger, anxiety, depression, guilt, nightmares, memory loss, etc.
Chapter 3 Hazards of Forensics Whether in or out of a lab, forensics can be hazardous work Physical dangers include exposure to substances, diseases and dangerous locations Emotional trauma may result from exposure to unusually violent events (plane crashes, etc.)
Chapter 3 Physical Hazards Exposure Risks Inhalation Entry into the lungs and bloodstream through the air Can take the form of sprays, mists, smoke, vapors, gases or fumes Most likely contamination route Ingestion Dangerous if agents are corrosive or poisonous Must be certain to wash hands after investigation Should never eat or drink within a scene
Chapter 3 Physical Hazards Exposure Risks Injection Certain crime scenes may contain items that can inject pathogens directly into the body Items may include boards with nails, needles, etc. Extreme caution sbould be exercised when in an area with sharp objects Mucous Membrane Contact Includes the skin, eyes, nose Certain chemicals may be able to penetrate skin or cause localized damage to the contaminated area Safety goggles and gloves are a must