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: Recognitionscene survey, documentation, collection Identificationcomparison testing done in the lab Individualizationevaluation and interpretation Reconstructionreporting 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 Websters) 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 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

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.