ETC Storage & Preservation 2 — Questions and Answers
Question 1: What is the primary reason biological evidence such as blood swabs must be air-dried before packaging?
- To destroy pathogens
- To prevent mold and bacterial degradation from moisture (Correct answer)
- To make DNA extraction easier
- To comply with OSHA shipping regulations
Correct answer: To prevent mold and bacterial degradation from moisture
Moisture trapped in sealed packaging promotes mold and bacterial growth that degrades biological evidence and can destroy DNA.
Question 2: Which storage environment is MOST appropriate for long-term preservation of latent fingerprint cards?
- Humid, warm room
- Cool, dry, dark environment (Correct answer)
- Freezer at -20°C
- Outdoor evidence locker
Correct answer: Cool, dry, dark environment
Latent fingerprint cards are best preserved in cool, dry, dark conditions to prevent fading of developed prints and degradation of the substrate.
Question 3: A technician needs to store a firearm recovered from a crime scene. What is the first step before placing it in the evidence locker?
- Test-fire the weapon
- Render it safe and document its condition (Correct answer)
- Apply fingerprint powder
- Photograph only the barrel
Correct answer: Render it safe and document its condition
Firearms must be rendered safe (verified unloaded) and their condition documented before storage to ensure officer safety and maintain evidentiary integrity.
Question 4: Which container is MOST appropriate for storing soil samples collected from a crime scene?
- Plastic zip-lock bag
- Sealed glass jar or metal can (Correct answer)
- Paper envelope
- Biohazard bag
Correct answer: Sealed glass jar or metal can
Glass jars or metal cans preserve volatile compounds in soil samples better than plastic, which can absorb or off-gas trace chemicals.
Question 5: What temperature range is recommended for storing DNA reference samples for long-term preservation?
- Room temperature (20–25°C)
- Refrigerator (2–8°C)
- -20°C or lower (frozen) (Correct answer)
- 40–50°C
Correct answer: -20°C or lower (frozen)
DNA reference samples are stored at -20°C or lower to halt enzymatic degradation and preserve sample integrity for future analysis.
Question 6: When storing digital evidence such as a hard drive, which environmental factor is most critical to control?
- Exposure to ambient light
- Static electricity and magnetic fields (Correct answer)
- Humidity above 80%
- Temperature above 30°C
Correct answer: Static electricity and magnetic fields
Static electricity and magnetic fields can corrupt or erase data on digital storage media, making anti-static packaging and shielded storage essential.
Question 7: An evidence technician discovers that a sealed package of drug evidence has been opened and resealed without documentation. This is BEST described as a:
- Minor administrative error
- Break in the chain of custody (Correct answer)
- Normal evidence review procedure
- Contamination event
Correct answer: Break in the chain of custody
Unauthorized opening and resealing without documentation constitutes a break in the chain of custody, which may render the evidence inadmissible.
ETC Storage & Preservation 2
What is the primary reason biological evidence such as blood swabs must be air-dried before packaging?