CFL Key & Lock Examination 2 — Questions and Answers
Question 1: When examining a key for evidence of impressioning, which surface area is most critical to document?
- The bow (head) of the key
- The tip of the key
- The blade's bitting marks and file contact traces (Correct answer)
- The key's thickness measurement
Correct answer: The blade's bitting marks and file contact traces
Impressioning leaves characteristic file marks and scratch patterns on the blade where the locksmith filed to fit the key to the lock.
Question 2: A forensic examiner finds bright, shiny scratches running longitudinally along a key's cuts. This pattern is MOST consistent with:
- Normal use wear
- Picking attempts with a tension wrench
- Dragging the key across a hard surface (Correct answer)
- Forced entry using a key extractor
Correct answer: Dragging the key across a hard surface
Longitudinal drag marks along the cuts typically indicate the key was scraped across an abrasive or hard surface, not normal insertion wear.
Question 3: Which type of key duplication method is most difficult to detect forensically because it leaves the fewest tool marks?
- Hand filing from a blank
- Key cutting machine duplication (Correct answer)
- Impressioning with wax
- Electrolytic deposition copying
Correct answer: Key cutting machine duplication
Machine-cut duplicate keys closely mimic the original bitting profile and show only machine cutter marks, which are minimal and difficult to distinguish from the original.
Question 4: What does the term 'bitting depth' refer to in key examination?
- The total length of the key blade
- The vertical measurement of each cut from the blade's surface (Correct answer)
- The horizontal spacing between cuts
- The angle of the key's tip bevel
Correct answer: The vertical measurement of each cut from the blade's surface
Bitting depth is the measured depth of each individual cut on the key blade, which determines which pins are elevated to the shear line.
Question 5: A Certified Forensic Locksmith compares two keys microscopically and finds identical bitting but different manufacturer codes stamped on the bow. This MOST likely indicates:
- The keys are from different keyways families
- One key is a duplicate made from the original (Correct answer)
- Both keys came from the same factory batch
- The stamps are decorative and not forensically significant
Correct answer: One key is a duplicate made from the original
Identical bitting with different stamps suggests one is a copy made to match the cuts of the original, as duplicating machines do not replicate manufacturer codes.
Question 6: What is the primary purpose of examining the keyway profile during a forensic lock analysis?
- To determine the lock's age
- To identify the manufacturer's country of origin
- To establish keyway compatibility and potentially link keys to a specific lock model (Correct answer)
- To measure the lock's tensile strength
Correct answer: To establish keyway compatibility and potentially link keys to a specific lock model
The keyway profile determines which keys can physically enter the lock, helping examiners link a suspect key to a particular lock or brand.
Question 7: During a forensic key examination, 'step cuts' refer to:
- Cuts that progressively deepen from tip to bow
- Secondary cuts perpendicular to the primary bitting
- Cuts made on both sides of the key blade (Correct answer)
- Damage caused by repeated forced entry attempts
Correct answer: Cuts made on both sides of the key blade
Step cuts (also called double-sided or paracentric cuts) are bitting cuts found on both the top and bottom edges of the key blade, used in higher-security key profiles.
CFL Key & Lock Examination 2
When examining a key for evidence of impressioning, which surface area is most critical to document?