Trace Evidence Stations Cards
Trace Evidence Stations
Case File #402
Warehouse Heist
STATION 1
The Stranded Suspect
EVIDENCE TYPE: HAIR
"A single strand of hair was found snagged on a broken window latch at the entry point."
Microscopic Observation:
Medulla: Absent or fragmented.
Cuticle: Imbricate (overlapping scales).
Cortex: Consistent pigmentation.
DETECTIVE TASK:
Based on the cuticle pattern and medulla, is this hair from a Human or an Animal? Explain your reasoning.
Cut Here
STATION 2
The Blue Thread
EVIDENCE TYPE: FIBER
"A small blue fiber was recovered from the victim's jacket. The suspect wore a similar blue fleece."
Burn Test Results:
- • Approaching Flame: Melts/shrinks
- • In Flame: Burns slowly
- • Residue: Hard, black bead
- • Odor: Chemical/Plastic
Microscope View:
Uniform diameter, perfectly smooth surface, no internal structures visible.
DETECTIVE TASK:
Is this a Natural fiber or a Synthetic fiber? What evidence supports this?
Trace Evidence Stations
Case File #402
STATION 3
Shattered Entry
EVIDENCE TYPE: GLASS
"A glass pane was broken from the outside. Fragments were found on the floor inside the warehouse."
Key Terms:
- • Radial Fractures: Extend outward from impact.
- • Concentric Fractures: Circles around impact.
DETECTIVE TASK:
Identify the fractures. If a second shot hit the glass, how could you tell which hole happened first?
Cut Here
STATION 4
The Dirty Secret
EVIDENCE TYPE: SOIL
"Muddy footprints led away from the warehouse. A suspect's car had soil caked in the wheel wells."
Crime Scene Soil:
Color: Dark Brownish-Red
pH Level: 5.5
Composition: High Clay
Suspect Car Soil:
Color: Dark Brownish-Red
pH Level: 5.4
Composition: High Clay
DETECTIVE TASK:
Does the soil match? Is soil considered "Individual" or "Class" evidence? Explain.
Trace Evidence Stations
Case File #402
STATION 5
Hit and Run
EVIDENCE TYPE: PAINT
"A suspect's car bumped a yellow bollard near the gate, leaving behind chips of paint."
Cross-Section:
- Clear Coat
- Base Coat (Navy Blue)
- Primer Surfacer
- Electrocoat Primer
DETECTIVE TASK:
Investigators found a chip with 4 layers. Why is more layers better for identification than one?
Cut Here
STATION 6
The Floral Fingerprint
EVIDENCE TYPE: POLLEN
"The suspect claims they were at a local city park. Pollen was found on their shoes."
Sample A (Shoes)
Reference:
- • Ragweed: Spiky (City Lots)
- • Pine: Double-bubble (Forests)
- • Lily: Oval (Parks)
DETECTIVE TASK:
Sample A shows spiky particles. Does this support the park alibi? Explain.
Trace Evidence Stations
Case File #402
STATION 7
Heavy Metal
EVIDENCE TYPE: METAL
"Tiny metal shavings were found near the forced safe. The suspect works as a machinist."
Analysis Report:
Magnetism: Positive | Acid Reaction: Bubbling
DETECTIVE TASK:
Are these filings Iron or Aluminum? How does this link the machinist suspect to the crime?
Cut Here
STATION 8
Dust to Dust
EVIDENCE TYPE: DUST
"Dust from the suspect's clothes was analyzed using a scanning electron microscope (SEM)."
Silica particles
Concrete debris
DETECTIVE TASK:
Does this match a Residential or Industrial setting? Why is this helpful?
Trace Evidence Log Worksheet
Evidence Log
Case File #402: Warehouse Heist Investigation
INSTRUCTIONS: Record detailed observations and conclusions for each station. Page 1: Stations 1-4. Page 2: Stations 5-8 + Conclusion.
STATION 1: HAIR ANALYSIS
Observations
Conclusions & Reasoning
STATION 2: FIBER ANALYSIS
Observations
Conclusions & Reasoning
STATION 3: GLASS ANALYSIS
Observations
Conclusions & Reasoning
STATION 4: SOIL ANALYSIS
Observations
Conclusions & Reasoning
Page 1 of 2
STATION 5: PAINT ANALYSIS
Observations
Conclusions & Reasoning
STATION 6: POLLEN ANALYSIS
Observations
Conclusions & Reasoning
STATION 7: METAL ANALYSIS
Observations
Conclusions & Reasoning
STATION 8: DUST ANALYSIS
Observations
Conclusions & Reasoning
Investigative Conclusion
Synthesize your findings. How strong is the case against the suspect? Which single piece of trace evidence provides the most definitive link to the scene?
Page 2 of 2
Trace Evidence Lab Tech Key
Lab Tech Key
Trace Evidence Scavenger Hunt Guide
Teacher Resource
Lab Setup Instructions
1
Place Station Cards in numbered locations around the room. Provide physical samples if possible (wool, polyester, soil) for tactile learning.
2
Review Locard's Exchange Principle: "Every contact leaves a trace." Emphasize that trace evidence is typically Class Evidence.
3
Pacing: 5-7 minutes per station. Ensure students use the Evidence Log to record both objective observations and logical conclusions separately.
Conclusions: Stations 1-4
Station 1: Hair
Human. Cuticle is imbricate (human/dog) but medulla is absent/fragmented (human). Animal hair typically has a wider medulla (>1/3 diameter).
Station 2: Fiber
Synthetic. Hard black bead residue and chemical odor are markers of synthetic materials. Uniform smooth shape confirms factory extrusion.
Station 3: Glass
First hole analysis. Fractures from a second impact will terminate at existing fracture lines. This establishes the sequence of entry events.
Station 4: Soil
Positive Match. pH and composition align. It is Class evidence because specific geologic features can be shared across multiple sites.
Conclusions: Stations 5-8
Station 5: Paint
High Specificity. Multiple layers (clear, base, primer) create a unique profile. While still class evidence, 4 layers is highly discriminating for a specific car.
Station 6: Pollen
Alibi Rebuttal. Ragweed (spiky) is a "weed" pollen common in vacant lots, not maintained parks. Suspect's location claim is likely false.
Station 7: Metal
Iron/Steel. Magnetic shavings link to the safe-breaking tool marks and the suspect's background as a machinist.
Station 8: Dust
Industrial Match. Concrete and glass dust particles are specific to construction/warehouse environments, not household settings.
Teaching & Facilitation Tips
Encourage students to use the term "Consistent with" rather than "Proves." Trace evidence is cumulative. Individually, these stations might be weak, but when all eight point to the same industrial context and the same suspect alibi failure, the case becomes compelling. Focus the debrief on why class evidence is still vital for narrowing suspect pools.
