Crime Scene Notes

Vocabulary


  1. Trace evidence – a small but measurable amount of physical material. 


  1. Locard’s Exchange Principle: When a person comes into contact with an object or another person, a cross-transfer of evidence can occur.  The intensity, duration, and nature of the exchange determines the amount of transfer.


  1. Direct evidence: firsthand observations


  1. Circumstantial evidence: indirect evidence that can be used to imply a fact but can’t be proved directly.

  1. Biological (example: body fluids, hair, plant parts)

  2. Physical (examples: fingerprints, footprints, tool marks, bullets, fiber)



Seven S’s of Crime-Scene Investigations

  1. Securing the scene – first responder protects the scene until help arrives

  2. Separating the witnesses – Not be allowed to talk with each other to avoid collusion

  3. Scanning the scene – determine where photos are taken

  4. Seeing the scene – taking photos from a variety of perspectives so everything is seen

  5. Sketching the scene – rough sketch of the scene with body and evidence with scale

  6. Searching for evidence – follow a search pattern and mark evidence, then photograph it

  7. Securing evidence – all evidence must be properly packaged, sealed, and labeled.

  1. Chain of custody and evidence log attached


Evidence Log

  1. Case number

  2. Item inventory number

  3. Description of item

  4. Name of suspect

  5. Name of victim

  6. Date and time

  7. Signature of person recovering the evidence

  8. Signature of any witnesses


Chain of custody

  1. Evidence log and evidence placed in baggie

  2. Baggie sealed with tape

  3. Person in charge signs name on tape

  4. Evidence bag given to next person

  5. After analysis, bag is resealed with new tape and new signature