Impression Evidence and Collection Methods
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Impression Evidence and Collection Methods

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Questions and Answers

What is the primary focus of the Impression Section examiners?

  • Identifying handwriting in questioned documents
  • Comparing known shoes or tires to impressions from crime scenes (correct)
  • Comparing known substances to chemical evidence
  • Analyzing blood samples for DNA matching
  • Which type of impression can be analyzed as a three-dimensional impression?

  • Impressions on car windows
  • Impressions on cardboard
  • Impressions on glass surfaces
  • Impressions in soil or snow (correct)
  • What is NOT one of the purposes of examining impression evidence?

  • Identifying make, design, and size of footwear or tires
  • Determining if there are sufficient design features for comparison
  • Identifying the presence of fingerprints (correct)
  • Comparing questioned impressions to known objects
  • What must be considered when making a positive identification between the source and impression?

    <p>The individual characteristics and sufficient details of the impression</p> Signup and view all the answers

    Which conclusion can an examiner potentially reach from analyzing impression evidence?

    <p>Various levels of association including identification, exclusion, or inconclusive results</p> Signup and view all the answers

    Why is quick recovery of impression sources important?

    <p>To ensure continuous use does not alter the identifying characteristics</p> Signup and view all the answers

    What type of prints are categorized as two-dimensional impressions?

    <p>Impressions on solid surfaces like floors or car hoods</p> Signup and view all the answers

    What elements are evaluated to identify a specific tire or footwear item?

    <p>Physical size and wear/manufacturing characteristics</p> Signup and view all the answers

    What should be done to minimize ambient light when photographing impressions?

    <p>Drape a cloth over the tripod to create a tent</p> Signup and view all the answers

    What is the purpose of taking photos with different aperture settings?

    <p>To ensure proper exposure through bracketing</p> Signup and view all the answers

    How many feet of circumference should be documented for tire impressions?

    <p>At least six feet</p> Signup and view all the answers

    What should be used to enhance contrast in snow impressions?

    <p>Black fingerprint powder</p> Signup and view all the answers

    Which flash settings are recommended when photographing impressions?

    <p>Manual settings</p> Signup and view all the answers

    What type of camera is recommended for photographing three-dimensional impressions?

    <p>Digital SLR camera</p> Signup and view all the answers

    What is the preferred image format for capturing evidence photographs?

    <p>RAW</p> Signup and view all the answers

    What should be avoided when using primer spray paint on snow impressions?

    <p>Spraying directly into the impression</p> Signup and view all the answers

    Why is it important to ensure the scale is at the same depth as the impression?

    <p>To provide accurate comparison in scale</p> Signup and view all the answers

    Why is it important to photograph impressions at a 1:1 ratio?

    <p>To maintain detail and resolution</p> Signup and view all the answers

    What is a common technique to ensure continuity when taking multiple photos of an impression?

    <p>Overlapping the photos</p> Signup and view all the answers

    What should be included in the examination quality photographs alongside the impression?

    <p>A measuring scale</p> Signup and view all the answers

    How should the camera be positioned when photographing the impression?

    <p>Directly overhead and parallel to the impression</p> Signup and view all the answers

    What is the recommended positioning of the measuring scale in relation to the impression?

    <p>Next to the impression without covering it</p> Signup and view all the answers

    Why should impression evidence be prioritized for early consideration?

    <p>It is easily contaminated.</p> Signup and view all the answers

    What angle is recommended for holding the flash when photographing impressions?

    <p>Approximately 10°, 30°, and 45°</p> Signup and view all the answers

    What type of scale is preferably used for impressions?

    <p>90° or L-shaped scale</p> Signup and view all the answers

    What is recommended to practice before collecting evidence impressions?

    <p>Casting techniques on a test impression.</p> Signup and view all the answers

    What should be done with moist or damp impressions when collecting evidence?

    <p>They cannot be collected with the EDPL.</p> Signup and view all the answers

    What type of media is preferred for submitting images of impressions?

    <p>CD or DVD in TIFF file format.</p> Signup and view all the answers

    How should shoes and tires be packaged for evidence submission?

    <p>Shoes in paper bags, each tire separately.</p> Signup and view all the answers

    What should you avoid using to package the dust lift on EDPL film?

    <p>Plastic containers</p> Signup and view all the answers

    Which method is NOT suitable for recovering powder developed impressions?

    <p>EDPL</p> Signup and view all the answers

    What characteristic of Stat-LiftTM is important for its function?

    <p>It is statically charged</p> Signup and view all the answers

    What should you do after lifting an impression with tape?

    <p>Hold it over a light and dark surface</p> Signup and view all the answers

    Which tool is specifically mentioned as effective for lifting dust impressions?

    <p>Gel lifters</p> Signup and view all the answers

    What does dental stone do when applied to visible residue impressions?

    <p>Absorbs the residue material</p> Signup and view all the answers

    What type of materials can dental stone successfully recover impressions from?

    <p>Visible residue from mud or thick materials</p> Signup and view all the answers

    What is the advantage of using wider fingerprint tape for lifting impressions?

    <p>It reduces the chance of overlapping</p> Signup and view all the answers

    Study Notes

    Impression Evidence

    • Impression evidence can include shoe or tire impressions in a variety of mediums.
    • Three-dimensional impressions occur in materials like soil, snow, sand, and mud.
    • Two-dimensional impressions are found on solid surfaces, such as floors, counters, car hoods, and paper
    • Examination aims to determine if there are discernible characteristics for comparison
    • Examinations can identify make, design, physical size, wear/manufacturing characteristics, and randomly acquired features
    • Comparison of questioned impressions with a known object can determine if the object made the impression.
    • Possible conclusions include identification, exclusion, or various levels of association.

    Collection Guidelines

    • Three-Dimensional Impressions (e.g., in soil)

      • Method I - Photographic Documentation

        • Use a digital SLR camera with the ability to attach an off-camera flash.
        • Take photos in the camera's RAW format and convert to TIFF for laboratory submission.
        • Use the highest megapixel camera available to achieve 300PPI resolution at size (1:1).
        • Photograph impressions using a tripod and aligning the sensor plane directly over the impression.
        • Step 6: Include a scale alongside the impression containing identification information. Bury the ruler to approximately the same depth as the impression.
        • Step 7: Use low oblique lighting with the flash held approximately three feet from the impression. Photograph at 10°, 30°, and 45° angles to highlight the impression.
        • Step 8: Bracket the series of photos, photographing at various aperture settings, such as f8, f11, and f16.
        • Step 9: For tire impressions, ensure the entire circumference is documented with overlapping photos.
        • Step 10: Lightly sprinkle black fingerprint powder onto snow impressions for contrast. Use black or gray primer paint for highlight purposes.
      • Method II - EDPL Lifting

        • Not recommended for moist or damp impressions. Practice lifting techniques prior to evidence collection.
      • Method III - Lifts

        • Gel Lifters are latex with a bonded adhesive layer suitable for lifting and preserving dust impressions.
        • Stat-LiftTM is a statically charged film that’s commercially available for lifting dust impressions.
        • Wide fingerprint tape is a viable option for two-dimensional impressions. Dust impressions with fingerprint powder before lifting.
      • Method IV - Dental Stone Casting

        • Best for visible residue impressions. Dental stone absorbs residue material and cleans the surface.
        • Cast in the same manner prescribed for three-dimensional impressions.

    Submission Reminders

    • Prioritize evidence by searching for it at the approach, entry/exit ways, path through the scene, escape route, near other impressions, and on floors, walls, doors, and the roof. Protect impressions from contamination.
    • Practice new techniques on test impressions before working with evidence.
    • Use the correct method based on the type and condition of the impression.
    • Submit images on a CD or DVD in TIFF format.
    • Package shoes in paper bags and each tire separately.

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    Description

    Explore the key concepts of impression evidence, including shoe and tire impressions in different materials. Learn about the characteristics examined during forensic analysis and the methods for collecting three-dimensional impressions. This quiz will test your understanding of the identification and comparison process in forensic science.

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