1 Forensic Science Fundamentals Investigations 2 e Chapter

1 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

a m en tal s & In ve sti ga tio ns, C ha pt er 22 o o Catching killers trace evidence http: //www. smithsonianchannel. com/shows/c atching-killers/traceevidence/1003122/3375550#the-originalsherlock-holmes FF soiled plans https: //www. youtube. com/watch? v=u. Y 4 GCSJ r. RAM FF material witness https: //www. youtube. com/watch? v=pp. GWy 2 k CKjg Trace evidence links https: //sciencespot. net/Pages/kdzforsci 2. html Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Chapter 2 Crime-Scene Investigation and Evidence Collection By the end of this chapter you will be able to: 2. 1 Summarize Locard’s Principle of Exchange. 2. 2 Identify four examples of trace evidence. 2. 3 Distinguish between direct and circumstantial evidence. 2. 4 Identify the types of professionals who might be present at a crime scene. 2. 5 Summarize the seven steps (seven S’s) of a crime-scene investigation. 3 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Chapter 2 Crime-Scene Investigation and Evidence Collection By the end of this chapter you will be able to: 2. 6 Explain the importance of securing the crime scene. 2. 7 Identify the methods by which a crime scene is documented. 2. 8 Demonstrate proper technique in collecting and packaging trace evidence. 2. 9 Explain what it means to map a crime scene. 2. 10 Describe how evidence from a crime scene is analyzed. 4 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Chapter 2 Vocabulary o o o o 5 chain of custody circumstantial evidence class evidence crime-scene investigation crime-scene reconstruction datum point direct evidence o o o o Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 first responder individual evidence paper bindle primary crime scene secondary crime scene trace evidence triangulation All rights Reserved Cengage/NGL/South-Western © 2016

o o 6 https: //www. youtube. com/watch? v=tqt. S 4 w. Mf ZYo&list=PLHh. Ze. HMIx 0 DK 25 ey 3 W 4 Yx 308 YANo 7 ey. C&index=40&t =230 s texas rangers csi techniques https: //www. youtube. com/watch? v=Jgzdh. UA Jr. BA&list=PLHh. Ze. HMIx 0 DK 25 ey 3 W 4 Yx 308 YANo 7 ey. C&index=35&t =112 s intro to crime scenes Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Principle of Exchange o Locard's Principle of Exchange • • • 7 When a person comes in contact with an object or another person, a cross-transfer of physical material can occur. Trace evidence left behind: hair, paint, blood…. The intensity, duration, and nature of the entities and contact determine the extent of the transfer. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Types of Evidence o Direct evidence • First-hand observations o o Circumstantial evidence • • 8 Eyewitness accounts Police video cameras confessions Indirect evidence that can be used to imply a fact but that does not prove it Suspects gun at scene Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

9 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Types of Evidence (continued) o Class evidence • • o Individual evidence • • 10 Narrows an identity to a group of persons or things Blood type Narrows an identity to a single person or thing Fingerprint or DNA Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

The Crime-Scene Investigation Team o o o 11 Police officers Crime-scene investigators Medical examiners Detectives Specialists Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

The Seven S’S of Crime-Scene Investigation 1. 2. 3. 4. 5. 6. 7. 12 Securing the Scene Separating the Witnesses Scanning the Scene Seeing the Scene Sketching the Scene Searching for Evidence Securing and Collecting Evidence Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

The Seven S’s of Crime Scene Investigation 1. Secure the scene – Done by the 1 st responding police: checking safety of individuals and preserving evidence 2. Separate the witnesses - Witnesses must not be allowed to talk to one another. 3. Scan the scene - Determine the primary and secondary crime scenes and decide what to photograph. 4. Seeing the scene - Photos of the overall area and 13 close up photos should be taken. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

The Seven S’s of Crime Scene Investigation 5. Sketch the scene - A rough sketch and a neater final copy of the crime scene drawn to scale must be made. 6. Search for evidence - A spiral, grid, linear or quadrant pattern should be walked and location of evidence marked, photographed and sketched. 7. Secure the collected evidence - All evidence must be properly packaged, sealed and labeled using specific techniques and procedures. 14 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

15 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

16 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Packaging Evidence o 17 The paper bindle is ideal packaging for small, dry, trace evidence. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Packaging the evidence Paper bindle Crease a clean paper and place evidence in the X position 2. Fold in the left and right sides, and then fold in the top and tuck it into the bottom - securely 3. Put the bindle into a plastic or paper evidence bag affixing a seal (tape) over the opening 4. Write your name diagonally across the seal 1. Foren sic Scienc e: Funda mental s& Investi gation s, Chapt er 2 18 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Chain of Custody Maintaining a chain of custody log is essential to present credible evidence in court 19 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Chain of Custody (cont’d. ) 1. Bag the evidence Foren sic Scienc e: Funda mental s& Investi gation s, Chapt er 2 20 Add identification Seal it Sign it across the sealed edge 2. Sign over to a lab technician Open bag on non-sealed edge 3. Return items to the evidence bag Seal evidence bag in another bag 4. Sign the evidence log Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Mapping the Outdoor Crime Scene o Datum Points • • • 21 Permanent fixed point of reference Tree or corner of building Subdatum Points – area marked at corner of scene measured from datum point Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

22 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

23 Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Mapping the Outdoor Crime Scene (continued) o 24 Measuring and Marking Evidence Positions Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Analyze the Evidence o o Foren sic Scienc e: Funda mental s& Investi gation s, Chapt er 2 25 forensic lab – where evidence is processed revieling facts about the crime. Lead detective aims to see how facts fit into the crime scenario Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Analyze the Evidence o 26 Forensic lab technicians are specialized to process only one type of evidence. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Crime-Scene Reconstruction o Crime scene reconstruction involves: • • o 27 Forming a hypothesis of the sequence of events from before the crime was committed through its commission Comparing the evidence to witnesses statements Investigators need to maintain an open mind as they examine all possibilities. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Staged Crime Scenes o Commonly staged types of crime scenes include: • • • 28 Arson : murder/burglary Murder staged to look like a suicide Burglary: insurance money Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Staged Crime Scenes Was the crime scene staged? Consider: o o o Foren sic Scienc e: Funda mental s& Investi gation s, Chapt er 2 29 o Does the type of wound match the weapon? Could the wound be easily self-inflicted? What were the mood and actions of the victim before the event? What were the mood and actions of the suspect before the event? Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Summary o o o 30 Locard’s Principle of Exchange states that contacts between people and objects during a crime can result in a transfer of material. Evidence may be direct, as in eyewitness accounts, or circumstantial, which does not directly support a fact. Evidence may be physical or biological. Trace evidence is a small amount of physical or biological evidence. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Summary (continued) o o o 31 A crime-scene investigation team consists of police officers, detectives, crime-scene investigators, medical examiners, and specialists. A crime-scene investigation consists of recognizing, documenting, photographing, and collecting evidence from the crime scene. First-responding officers must identify the extent of a crime scene, including primary and secondary scenes when possible, secure the scene(s), and segregate witnesses. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016

Summary (continued) o o 32 After examining the crime scene(s) and identifying evidence, the crime-scene investigators document the scene(s) with photographs and sketches. Crime scene(s) are sometimes precisely mapped to ensure that no evidence is overlooked. Evidence must be properly handled, collected, and labeled so that the chain of custody is maintained. Evidence is analyzed in a forensic laboratory, and the results are provided to detectives, who develop a possible crime-scene scenario. Forensic Science: Fundamentals & Investigations, 2 e Chapter 2 All rights Reserved Cengage/NGL/South-Western © 2016