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Investigators must recognize, preserve, and record physical evidence in its original condition. They must also protect t

Chapter 2: Crime Scene. Investigators must recognize, preserve, and record physical evidence in its original condition. They must also protect the area. Three recording methods: 1. Photography 2. Sketches 3. Notes. Photography: The crime scene should NOT be altered

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Investigators must recognize, preserve, and record physical evidence in its original condition. They must also protect t

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  1. Chapter 2: Crime Scene Investigators must recognize, preserve, and record physical evidence in its original condition. They must also protect the area

  2. Three recording methods: 1. Photography 2. Sketches 3. Notes

  3. Photography: • The crime scene should NOT be altered • pictures are taken from all angles • close up pictures of injuries and weapons are taken • after the body is removed from the scene, the surface beneath the body is photographed • all physical evidence is photographed to show position and location relative to the crime scene • Videotaping is becoming more common, but the still photo is better for detail

  4. Sketches: • A rough sketch is initially created. • Must contain an accurate depiction of the dimensions of the scene and location of all objects having a bearing on the case. • A finished sketch is created from the rough sketch for aesthetic reasons only.

  5. ROUGH SMOOTH CRIME SCENE SKETCHING 5

  6. Notes: • detailed written description of the crime scene. • written location of physical evidence recovered. • identify the time an item of physical evidence was discovered, by whom, how, and by whom it was packaged and marked. • sufficient detail needs to be recorded…may be referred to years later. • tape recording notes • narrating a video tape • tapes must be transcribed at some point

  7. What Physical Evidence is Collected? • massive objects – small traces • collect any POTENTIAL carriers of trace evidence • vaccuum sweepings • all clothing worn by participants in a crime • fingernail scrapings from individuals • collection in the autopsy room from dead victim • Tissues and organs retained • clothing • fingernail scapings • head and pubic hair • blood • vaginal, anal, and oral swabs • recovered bullets • hand swabs from shooting victims

  8. Procedures for collecting and Packing Evidence • Proper technique is important to make sure that the evidence doesn’t change over time. • Should be submitted to lab intact • Each item is packaged separately • a. liquids and arson remains are stored in airtight containers • b. biological evidence is stored in breathable containers so it can dry out. Then it is bindled. • A paper bindle (aka “druggist fold”) is • folded around the evidence

  9. Maintain the Chain of Custody This is a list of people who came in possession of an item of evidence. This is necessary when evidence is presented in court. This should be kept to a minimum.

  10. Obtain Standard/Reference Samples A “standard” allows the forensic scientist to compare physical evidence to other known sources. Examples: Hit and run Hair DNA A “substrate control” is a sample of material close to where physical evidence was collected. This ensures that this material does not interfere with the analysis of the physical evidence. Examples: shirt where blood was found

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