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Microscopic Procedures

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The following should be addressed prior to any microscopic comparisons:

  • Review laboratory protocols, as needed.
  • Complete administrative requirements:
    • Chain of custody
    • Marking of evidence
    • Laboratory case identifiers
    • Investigative file identifier
    • Examiner identity
    • Quality assurance
  • Follow laboratory safety protocols.
  • Determine the presence of trace evidence and follow laboratory protocol for collection.

    Examples of trace evidence include
    • paint,
    • glass,
    • blood,
    • bone,
    • soft tissue,
    • hair,
    • fibers,
    • wood,
    • metal smears,
    • masonry,
    • stone.
  • Determine if latent fingerprint examinations should be performed prior to toolmark examinations.
  • Determine if other examinations (not requested) should be performed. If so, coordinate with the investigator.
  • After the requirements dictated by trace evidence and latent fingerprints have been addressed, the toolmarked area can be cleaned:
    • Paint may be removed by soaking the tool in alcohol or acetone.
    • Plaster may be removed by soaking the tool in 15 percent acetic acid.
    • Loose material may be removed by rinsing the tool in water or methanol.
    • Blood and other biohazards may be removed by soaking for at least one minute in a 10 percent bleach solution.

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