IL

Notes on Physical Evidence, Documentation, and Packaging Procedures

Overview

  • Topic: Rules of evidence, physical evidence, and documentation procedures as presented in the module two PowerPoints and lab manual references.
  • Emphasis on practical skills for crime-scene documentation, evidence collection, labeling, sealing, and chain of custody.
  • Several real-world examples used to illustrate what can count as physical evidence and how to describe it with precision.

What is Physical Evidence?

  • Physical evidence is anything that is physically real and can be touched, picked up, and analyzed.
  • Common instinctive ideas of evidence items at a crime scene include blood, fingerprints, a gun, or a knife. These are typical but not exclusive.
  • Also include non-traditional items: sweatshirts, water bottles, T-shirts, or even a peach. The list is broad because any tangible object at the scene can be evidence if it helps prove or disprove facts.
  • Physical evidence can help locate a suspect or reconstruct the events of the crime, even if it doesn’t perfectly match a witness’s account.
  • Do not develop tunnel vision by only looking for the obvious items; be open to a wide range of potential evidence.

Examples and Categories of Evidence

  • Typical items at crime scenes: blood, fingerprints, weapons (gun, knife), etc.
  • Non-traditional examples mentioned: a peach, a water bottle, dirt, pieces of trash, a T-shirt, a sweatshirt.
  • A case example used: suspect robbed someone, sat down and ate (peach, chicken wings, soda). DNA swabs were taken from the peach and chicken wing to identify the suspect.
  • Additional categories to study later: trace evidence (hair, fibers, skin cells), impression evidence (tool marks, tire/shoe impressions), blood/biological evidence.
  • Broad principle: physical evidence can be any tangible material found at the scene that can be analyzed to support or refute facts.

Standard/Reference Samples

  • When collecting evidence, also collect standard or reference samples.
  • Purpose: have known comparisons to eliminate suspects or to identify substances more accurately (e.g., paint, blood, or fingerprints).
  • Example: hit-and-run with paint transfer. Collect both suspect’s paint and victim’s paint to compare and differentiate.
  • Blood, fingerprints, hair, and DNA can require reference samples to confirm results.
  • Concept: “standard or reference samples” help distinguish between similar samples and support conclusions.

Substrates and Standard Protocols

  • Substrate: the uncontaminated surface of a material near the evidence; important for preserving context and for control/reference sampling.
  • For blood: photograph first, then test to confirm it is blood. When collecting, take a sample of the blood and a sample of the surface it’s on (the substrate) as a reference.
  • Control/reference samples help ensure analyses are valid and defensible in court.

Identification and Forensic Theory

  • Quote from Richard Safferstein: Identifications have the purpose of determining the physical or chemical identity of a substance with as near absolute certainty as existing analytical techniques will permit.
  • Practical meaning: you are limited by available analytical techniques; collect as much as possible to support a robust analysis and identification (e.g., DNA, fingerprints).
  • Emphasizes comprehensive collection of evidence to enable identification and linkage to suspects or events.

Describing Evidence: Detail and Precision

  • Forensic description must be highly detailed, not vague.
  • Example transformation from simple to precise: instead of saying “a phone,” describe: "a Panasonic cordless home phone that is white and silver with a belt clip." Include model, color, and distinguishing features.
  • If there is something on the item (e.g., a red substance), describe it specifically and note its condition and location.
  • When an item could be valuable, avoid definitive claims about its material (e.g., gold vs. fake gold). Use qualifiers like "yellow metal" or "consistent with pearls" rather than asserting authenticity.
  • Use language that allows for uncertainty: terms like "consistent with," "resembles," or "possibly" rather than definitive statements.
  • Example descriptions:
    • Evidence item 5: "yellow metal chain necklace" (avoid assuming real gold).
    • Evidence item 6: "necklace containing small spherical beads consistent with pearls".
    • Jewelry example: when a ring may be diamonds but could be cubic zirconia, describe as "a white metal ring containing clear gems consistent with diamonds".
  • For weapons: identify general type with distinguishing parts (e.g., revolver vs. semi-automatic pistol) and avoid mislabeling components.
  • Writing on documents: describe textual content, photograph before any chemical processing for fingerprints, and record everything written on the document.
  • If unsure about a feature (e.g., whether a hole is a bullet hole), describe as a hole and provide measurements rather than assuming the cause.

Detailed Evidence Descriptions and Practice

  • In-lab exercise (pages 8–10 in the lab manual): document evidence items thoroughly with precise descriptions.
  • Example description: two yellow metal circular rings (wedding bands) on top of one another; top ring slanted; bottom ring level with the tabletop; top ring width ~1.5 cm; bottom ring width ~1 cm. Location example: 1234 Main Street, Northeast bedroom, on the mattress. You may simulate the location details for learning purposes.
  • The importance of specificity: include exact location within a site (inside/outside, room, furniture), not just a broad address.
  • If you are unsure about a term, consult colleagues (e.g., a range master or firearms specialist) but avoid sharing photos via personal devices or social media.
  • Do not post crime-scene photos on personal devices or share them publicly; photos should come from work-issued cameras only.
  • Photos or information from personal devices can be discoverable and harmful in court.

The Evidence Bag and Packaging Process

  • Page 11 shows an example of an evidence bag and its contents.
  • When collecting an item, you fill out the front of the bag first, then place the item inside.
  • Sealing process:
    • After placing the item inside, seal with evidence tape across the back.
    • Write your initials and the date of sealing on the bag.
  • Chain of custody: the document tracking everyone who has handled the evidence from the crime scene to the courtroom.
  • The property room is responsible for managing the chain of custody, issuing items for further analysis, and ensuring seals remain intact.
  • If another examiner opens the item for processing (e.g., to process fingerprints), a new seal is placed after their work, with their initials and seal date.
  • Multiple tapes and seals on a bag can occur as different people handle the evidence; each seal preserves the chain-of-custody integrity.
  • It is critical to seal the bag with a definite, clearly labeled seal and to initial and date the seal to prevent tampering and to document accountability.

Handling, Instructions, and Ethical Considerations

  • Use department-issued cameras for crime-scene photography; avoid personal devices.
  • Do not post or share images of the scene, bodies, or evidence; ensure all sharing is authorized and appropriate.
  • Be mindful of the chain of custody and always document who handled the evidence and when.
  • Recognize the ethical and legal implications of documentation errors or unverified statements in reports.

Lab Manual and Course Workflow References

  • Physical Evidence Lab (Pages 8–10):
    • Task: Describe how to document certain evidence items in a thorough, detailed manner.
    • Example: the two yellow rings with precise measurements and positioning.
  • Evidence Bag Example (Page 11):
    • Demonstrates front-fill, item placement, back-seal with tape, and initials/date.
    • Highlights the chain of custody workflow and the role of the property room in tracking evidence.
  • Practical outcome: develop a habit of precise language, accurate location descriptions, and proper packaging to ensure admissibility in court.

Quick Tips for Exam Preparation

  • Always describe items with specificity: model, color, features, condition, and precise location.
  • Use non-definitive language when uncertain: "consistent with" instead of "is" or "is not".
  • Document the scene before processing for fingerprints or other analyses.
  • Photograph evidence and scene before moving items; maintain meticulous notes about order of operations.
  • When describing a non-obvious item (e.g., a hole in wood), provide measurements and describe context rather than making a definitive claim.
  • Practice writing full, narrative-style descriptions (as if testifying) to develop the ability to articulate details clearly under cross-examination.
  • Regularly review the lab manual pages referenced (8–10 for documentation, 11 for bag example) to reinforce correct procedure.

Practice Prompts (for quick recaps)

  • Describe an evidence item in a Pan-asonic cordless home phone with color, model cues, and any unique features that could help identify it in court.
  • How would you document a glass containing a clear liquid that is not conclusively identified as water? Include wording that avoids definitive statements.
  • Explain the difference between floor vs. ground in scene descriptions and why accuracy matters in court testimony.
  • Outline the steps for sealing an evidence bag and the role of initials and date in maintaining chain of custody.
  • Give an example of a standard/reference sample collection scenario (paint transfer in a hit-and-run) and explain how it helps to identify or eliminate a suspect.

References and Final Notes

  • The discussion emphasizes a comprehensive, meticulous approach to physical evidence and its documentation.
  • Students should consult the lab manual for the specific page numbers and exercises mentioned (pages 7–11) as a practical guide for completing assignments and preparing for exams.
  • Always ensure that descriptions are unambiguous, verifiable, and supported by proper documentation and photographic evidence.