CMI Evidence Collection & Forensic Analysis 3 — Questions and Answers
Question 1: When a vessel's Voyage Data Recorder (VDR) is secured after a casualty, what is the first priority before downloading data?
- Play back the audio immediately to hear bridge communications
- Document the capsule's condition, seal number, and create a bit-for-bit forensic copy before analysis (Correct answer)
- Connect the VDR directly to a laptop and extract files using standard software
- Remove the capsule from the vessel and deliver it to the manufacturer
Correct answer: Document the capsule's condition, seal number, and create a bit-for-bit forensic copy before analysis
Creating a verified forensic image preserves the original data integrity and allows the original capsule to remain untouched as the evidentiary master copy.
Question 2: In a flooding casualty investigation, an investigator discovers a through-hull fitting with a cracked seacock body. What metallurgical analysis would best determine if the failure was pre-existing or sudden?
- Visual inspection of corrosion deposits alone is sufficient
- Scanning electron microscopy (SEM) to examine fracture surfaces for fatigue marks, stress corrosion, or overload failure patterns (Correct answer)
- Hardness testing using a Rockwell scale on the undamaged portion
- X-ray fluorescence (XRF) to determine material composition only
Correct answer: Scanning electron microscopy (SEM) to examine fracture surfaces for fatigue marks, stress corrosion, or overload failure patterns
SEM examination of fracture surfaces can distinguish fatigue cracks (beach marks, striations) from sudden overload failures, establishing whether the defect was progressive or acute.
Question 3: A marine investigator needs to establish the exact time a vessel's engine room bilge alarm activated. Which source provides the most reliable timestamp for this determination?
- The engineer's personal recollection during interview
- The integrated alarm and monitoring system (AMS) electronic log with UTC-synchronized timestamps (Correct answer)
- The chief engineer's handwritten watch log
- Radio communications recordings from the vessel
Correct answer: The integrated alarm and monitoring system (AMS) electronic log with UTC-synchronized timestamps
An AMS electronic log provides automated, UTC-synchronized timestamps that are more reliable than human recollection or manually recorded entries.
Question 4: During a collision investigation, both vessels' AIS tracks are examined. What limitation of AIS data must be considered when reconstructing the incident?
- AIS only records vessel name and MMSI, not position data
- AIS position reports are transmitted at intervals, so the track interpolates movement between transmissions and may not reflect instantaneous maneuvers (Correct answer)
- AIS data is encrypted and cannot be accessed by marine investigators
- AIS only functions in international waters, not in coastal zones
Correct answer: AIS position reports are transmitted at intervals, so the track interpolates movement between transmissions and may not reflect instantaneous maneuvers
AIS transmits at intervals based on speed and vessel type, meaning the reconstructed track interpolates position between actual transmissions and can miss rapid course or speed changes.
Question 5: An investigator collects fabric samples from a suspected arson fire aboard a yacht. What is the proper method for preserving these samples for accelerant detection?
- Place samples in paper bags and leave open to air-dry
- Seal samples in clean, unused paint cans or nylon bags to prevent accelerant evaporation (Correct answer)
- Wrap samples in plastic film and store at room temperature
- Immerse samples in distilled water to prevent combustion
Correct answer: Seal samples in clean, unused paint cans or nylon bags to prevent accelerant evaporation
Airtight containers such as clean paint cans or nylon evidence bags prevent volatile accelerant compounds from evaporating before laboratory analysis.
Question 6: What is the significance of finding high concentrations of carbon monoxide in a deceased crew member's carboxyhemoglobin level during a post-mortem examination?
- It indicates the victim drowned before the fire reached them
- It indicates the victim was alive and breathing in smoke-filled air, confirming they were alive during the fire (Correct answer)
- It proves the victim was outside the vessel when the fire started
- It is irrelevant to a marine fire investigation
Correct answer: It indicates the victim was alive and breathing in smoke-filled air, confirming they were alive during the fire
Elevated carboxyhemoglobin (COHb) levels confirm the victim inhaled combustion byproducts while alive, establishing they were present during the fire rather than already deceased.
Question 7: A marine investigator interviews a crew member who witnessed a man-overboard event. Under what circumstance should the investigator stop the interview and reschedule?
- When the crew member requests to have their union representative present
- When the witness appears acutely distressed, in shock, or physically impaired in a way that compromises their ability to provide reliable information (Correct answer)
- When the vessel's owner requests the interview be delayed
- When the witness cannot speak English as a first language
Correct answer: When the witness appears acutely distressed, in shock, or physically impaired in a way that compromises their ability to provide reliable information
Interviews conducted when a witness is in acute psychological distress or physically compromised produce unreliable information and may constitute a coercive or unfair process.
CMI Evidence Collection & Forensic Analysis 3
When a vessel's Voyage Data Recorder (VDR) is secured after a casualty, what is the first priority before downloading data?