Summary of Forensics Lesson: Investigative Processes (older version)

Summary of "Forensics Lesson: Investigative Processes (older version)"

This video provides a comprehensive overview of the investigative processes involved in forensic crime scene investigation, emphasizing the importance of maintaining evidence integrity from the crime scene to the courtroom. The lesson outlines key roles, procedures, and best practices that forensic investigators follow to ensure evidence is properly recognized, collected, preserved, and documented.

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Main Ideas and Concepts

• Forensic Science Begins at the Crime Scene:
  Evidence must be recognized and preserved correctly at the crime scene to be useful in court, as it can convict or exonerate suspects.
• Roles at the Crime Scene:
  Depending on jurisdiction and city size, various personnel may be present, including:
  • First responders (usually local police)
  • Crime Scene Investigators (may overlap with detectives in smaller towns)
  • District Attorneys (contacted if warrants are needed)
  • Medical Examiners (for death investigations)
  • Detectives (sometimes separate or combined with Crime Scene Investigators)
  • Specialists such as Anthropologists, psychologists, entomologists, depending on case specifics
• Importance of Training and Protocols:
  Investigators are highly trained to follow specific steps that maintain evidence integrity and document all actions to create a reliable Chain of Custody.
• Chain of Custody:
  A detailed paper trail documenting everyone who handles or comes into contact with evidence, crucial for maintaining its admissibility in court.

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Detailed Steps of Crime Scene Investigation

1. Securing the Scene:
   
   • First officer arrives and prioritizes medical assistance if needed.
   • Scene is secured using police tape, ropes, barricades.
   • Unauthorized persons (family, bystanders, media) are excluded.
   • Guards may be posted at entry/exit points, sometimes overnight.
   • Every person entering/exiting the scene is logged (crime scene log).
2. Separating the Witnesses:
   
   • Witnesses are separated to prevent collusion or influence on each other’s stories.
   • Investigators ask open-ended, non-leading questions (e.g., what was seen, where, when, other observations).
   • This step can happen simultaneously with securing the scene.
3. Scanning the Crime Scene:
   
   • A preliminary walkthrough to get an overview and identify potential evidence.
   • Evidence markers (placards) are placed to mark items or locations.
   • This step is quick and helps plan detailed searches.
4. Photographing the Crime Scene:
   
   • A dedicated photographer documents the scene extensively, often taking thousands of photos.
   • Photos must correspond with evidence markers and sketches.
   • Photography can occur alongside scanning.
5. Sketching the Crime Scene:
   
   • A rough sketch is made to show dimensions, locations, and relationships between evidence and features.
   • Modern technology (CAD programs, 3D scanning) is increasingly used to improve accuracy.
   • Sketches must align with photographs and evidence markers.
6. Searching the Crime Scene:
   
   • A detailed and systematic search using established patterns to find all evidence.
   • New evidence found is marked, photographed, and added to sketches.
   • Search patterns help ensure no evidence is missed.
7. Securing and Collecting Evidence:
   
   • Evidence is carefully collected, preserved in its original state as much as possible.
   • Investigators wear gloves to prevent contamination; gloves may be changed frequently.
   • Packaging varies by evidence type (large objects, trace evidence, biological samples).
   • Evidence must remain unmoved until documented thoroughly (notes, photos, sketches).
   • Evidence can come from primary, secondary, or tertiary scenes, or from autopsies.

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Packaging and Chain of Custody Details

• Proper Packaging:
  Different types of evidence require specific packaging (e.g., weapons, accelerants, hair samples).
• Small evidence like hair is packaged using a "bundle" or "druggist fold" to prevent loss.
• Packaging is sealed with evidence tape signed by the collector.
• Chain of Custody Log:
  Every transfer or handling of evidence is recorded with names, dates, times.
• The log travels with the evidence throughout its lifecycle.
• Failure to maintain this log can result in evidence being inadmissible in court.
• Lab Handling:
  Lab analysts repackage evidence with new seals and update the Chain of Custody.
• Old packaging is retained with the evidence for reference.

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Important Case Reference

• JonBenét Ramsey Case:
  Used as an example of failure to maintain evidence integrity and follow proper procedures, resulting in an unsolved murder case.

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Summary of Key Lessons

Maintaining the integrity of evidence from the crime scene to the courtroom is critical.
Proper securing, documenting, searching, collecting, packaging, and chain

Category

Educational

Video