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Forensic Science Introduction


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This was a presentation that was given to provide an over of the processes of crime scene investigation from first responder to laboratory processing.

  • the main power points was how to search for blood, they had to use the knifes that is similar to the knife the was used to kill, they had to use cimicals to exstrected the hand print and had to study who hand print was on the knife
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Forensic Science Introduction

  1. 1. Introduction to Forensic Science The Crime Scene
  2. 2. What to look for? <ul><li>Physical Evidence </li></ul><ul><ul><li>Any and all objects that can establish that a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator. </li></ul></ul>
  3. 3. CSI <ul><li>Crime Scene Investigator </li></ul><ul><ul><li>Must be educated on what to look for </li></ul></ul><ul><ul><ul><li>Over collection = overwhelmed laboratory personnel </li></ul></ul></ul><ul><ul><ul><li>Under collection = not enough evidence or missing important evidence </li></ul></ul></ul><ul><ul><li>Must be educated on proper collection techniques </li></ul></ul><ul><ul><ul><li>If the investigator cannot recognize physical evidence or cannot properly preserve it for laboratory examination, no amount of sophisticated laboratory instrumentation or technical expertise can salvage the situation. </li></ul></ul></ul>
  4. 4. Crime Scene: Step One-A <ul><li>Secure & Isolate the Crime Scene </li></ul><ul><ul><li>First responder must take on the responsibility of securing the crime scene </li></ul></ul><ul><ul><li>Anyone that enters a scene is a potential destroyer of physical evidence </li></ul></ul><ul><ul><li>Secure scene exceptions: </li></ul></ul><ul><ul><ul><li>Arresting perpetrator </li></ul></ul></ul><ul><ul><ul><li>Giving medical assistance </li></ul></ul></ul><ul><li>Difficult due to </li></ul><ul><ul><li>Media or press </li></ul></ul><ul><ul><li>Emotionally charged neighbors/family </li></ul></ul><ul><ul><li>Higher level police officials </li></ul></ul>
  5. 5. Crime Scene: Step One-B <ul><li>Lead Investigator </li></ul><ul><ul><li>Determines outer boundaries </li></ul></ul><ul><ul><li>Determines inner boundaries </li></ul></ul><ul><ul><ul><li>Satisfy important people </li></ul></ul></ul><ul><ul><li>Establish perpetrator’s path </li></ul></ul><ul><ul><li>Document & photograph obvious evidence </li></ul></ul><ul><ul><li>Perform an initial walk-through </li></ul></ul><ul><ul><ul><li>Gains an overview of the situation </li></ul></ul></ul><ul><ul><ul><li>Develop a strategy for examination </li></ul></ul></ul><ul><ul><ul><li>Document the entire scene </li></ul></ul></ul>
  6. 6. Crime Scene: Step Two <ul><li>Record the Scene </li></ul><ul><ul><li>The opportunity to permanently record the scene in its original state must not be lost </li></ul></ul><ul><ul><li>Methods of crime scene recording </li></ul></ul><ul><ul><ul><li>Photography </li></ul></ul></ul><ul><ul><ul><li>Sketches </li></ul></ul></ul><ul><ul><ul><li>Notes </li></ul></ul></ul><ul><ul><ul><li>Video (problems) </li></ul></ul></ul>
  7. 7. Crime Scene Photography <ul><li>Want unaltered condition </li></ul><ul><ul><li>If evidence was moved during medical assistance, do not move the evidence back to its original location. </li></ul></ul><ul><ul><li>Photograph in current location and document course of actions </li></ul></ul><ul><li>Three types of photographs taken </li></ul><ul><ul><li>Overview </li></ul></ul><ul><ul><li>Medium Range </li></ul></ul><ul><ul><li>Close Up </li></ul></ul>
  8. 8. Photography: Overview Pictures <ul><li>Photograph entire location </li></ul><ul><li>Photograph adjacent locations </li></ul><ul><li>Photograph locations leading to/from crime scene </li></ul><ul><li>Four corners method </li></ul><ul><ul><li>Take pictures from all four corners of the room to establish relationships between physical evidence items and crime scene </li></ul></ul>
  9. 9. Photography: Medium & Close Range <ul><li>Medium Range </li></ul><ul><ul><li>Used to show relationships between individual pieces of evidence </li></ul></ul><ul><li>Close Up </li></ul><ul><ul><li>Used to show details of the object itself </li></ul></ul>
  10. 10. Crime Scene Sketching <ul><li>Rough Sketch </li></ul><ul><ul><li>A draft representation of all essential information and measurements at a crime scene. </li></ul></ul><ul><ul><li>This sketch is drawn at the crime scene </li></ul></ul><ul><li>Measurements </li></ul><ul><ul><li>Rectangulation </li></ul></ul><ul><ul><li>Triangulation </li></ul></ul>
  11. 11. Crime Scene Sketching <ul><li>Finished Sketch </li></ul><ul><ul><li>A precise rendering of the crime scene, usually drawn to scale, drawn with concern for aesthetic appearance </li></ul></ul>
  12. 12. Crime Scene Note Taking <ul><li>Must Include </li></ul><ul><ul><li>Detailed written description of the scene with the location of items of physical evidence recovered </li></ul></ul><ul><ul><li>Time an item of physical evidence was discovered, by whom, how and by whom it was packaged and marked, and the disposition of the item after it was collected </li></ul></ul><ul><li>Notes may be the only way of refreshing investigators minds about crime scene for months or years after a crime has been processed </li></ul>
  13. 13. Systematic search for evidence <ul><li>Search Methods </li></ul><ul><ul><li>Spiral Search Method </li></ul></ul><ul><ul><li>Grid Method </li></ul></ul><ul><ul><li>Strip or Line Search </li></ul></ul><ul><ul><li>Quadrant or Zone Search </li></ul></ul>
  14. 14. Chain of Custody <ul><li>Continuity of possession must be established whenever evidence is presented in court as an exhibit. </li></ul><ul><li>Every person that handled or examined the evidence must be accounted for. </li></ul><ul><li>Authenticity and integrity of the evidence are in question. </li></ul>
  15. 15. Obtain Standard / Reference Samples <ul><li>Comparison samples must be provided along with evidence for comparison </li></ul><ul><ul><li>Soil, blood, glass, hair, fibers, etc </li></ul></ul>
  16. 16. CSI: Part Three <ul><li>Submit all evidence and reference samples to the crime laboratory </li></ul><ul><li>Must include a detailed request for forensic analysis </li></ul>