1. Forensic Science

2. 2 Protecting and Searching a Crime Scene The first officer to arrive at the scene of the crime automatically incurs the serious and critical responsibility of securing the crime scene from unauthorized intrusions. To prove that evidence is genuine and authentic, and to show that the object is what is claimed to be, a witness would have to be able to:

3. 3 Testify about where and how the object was obtained Identify the object by a serial number if a serial number is on the object Identify the object based upon personal knowledge and observations “If the evidence is not readily identifiable or is susceptible to alteration by tampering, substitution, or contamination, the party must establish a chain of custody.”

4. 4 The Chain of Custody Requirement To use physical evidence in a criminal or civil trail, the party offering the evidence has the burden of proving that the evidence is genuine and authentic. If the evidence (such as fingerprints or illegal drugs) could be subject to alteration by tampering, substitution, or contamination, a chain of custody must be shown.

5. 5 The Chain of Custody Requirement (Cont.) Chain of Custody: all persons who had possessions of the evidence must appear as witnesses to testify that the fingerprints or illegal drugs had not been tampered with, substituted, or contaminated while the witness had custody and control of the evidence.

6. 6 Situations Not Requiring a Chain of Custody A chain of custody is not required if the object to be used as evidence is not subject to alteration by tampering, substitution, or contamination.

7. 7 The following cases are examples: A chain of custody is not required in most shoplifting cases. A pistol was held to be admissible without showing a chain of custody. Twenty-two silver dollars stolen from a pawn shop were admitted for use in evidence although the victim couldn’t specifically identify them.

8. Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event. Physical evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession. Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm What will evidence collected at a scene do for the investigation? May prove that a crime has been committed Establish key elements of a crime Link a suspect with a crime scene or a victim Establish the identity of a victim or suspect Corroborate verbal witness testimony Exonerate the innocent. Give detectives leads to work with in the case Types of Evidence

9. 9 Trace evidence: The smallest things can make the biggest difference. Trace evidence: most often applied to minute or microscopic bits of materials that are not immediately apparent to even a trained investigator.

10. 10 Criminal crosses back porch, steps on brown paper bag Criminal breaks a small glass pane on the back door Struggles with homeowner

11. POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime. The CSI UNIT documents the crime scene in detail and collects any physical evidence. The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge. The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death. SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis. DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence. Source: http://science.howstuffworks.com/csi.htm Crime Scene Personnel

12. 7 S’s for Processing Crime Scene 1)Secure 2)Separate Witnesses 3)Scan the Scene 4)See the Scene 5)Sketch the Scene 6)Search for Evidence 7)Secure the Evidence

13. The Team Leader should observe and supervise the search while other team members perform the search. With a overlapping search items are unlikely to be missed. Strip Search: Commonly used when searching a large area looking for a large object. Several Explorers will stand in one long line and all walk the same direction. Stakes and string can also be used to create “lanes” for which each Explorer would be responsible. Spiral Search: Commonly used when looking for an object that is suspected to be a specific distance from another, for example: shell casing from a gun or an object thrown by hand from a specific location, but thrown in an unknown direction. A stake in the center with a string attached will assure proper distance and avoid overlapping already searched areas or missing areas not yet searched. Crime Scene Protocol

14. Grid Search: This is the most thorough search technique. Similar to a strip search but also done in opposite directions. Another example of a strip search. Another example of a grid search. Crime Scene Protocol

15. Step 1: Interview The first step in investigating a crime scene is to interview the first officer at the scene or the victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start. Step 2: Examine The second step in the investigation of a crime scene, which will help identify possible evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene. Step 3: Document The third step in the protocol involves creating a pictorial record of the scene as well as a rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene. Step 4: Process This is the last step in the protocol. The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory. Crime Scene Protocol Adapted from http://www.feinc.net/cs-proc.htm

16. Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass. Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials. Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva. Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons. Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires. Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects. Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock. Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin. Investigating the Evidence Source: http://www.isp.state.il.us/forensics/ Forensic Science disciplines at the Illinois State Police Crime Labs

17. Mock Crime Scene: http://www.masss.govhttp://www.masss.gov What evidence would you collect?