CFL Lock Identification & Key Systems 2 — Questions and Answers
Question 1: Which key system feature allows a single master key to operate locks that each have their own individual change key?
- Keyed-alike system
- Master key system (Correct answer)
- Restricted keyway system
- Interchangeable core system
Correct answer: Master key system
A master key system uses a hierarchical bitting arrangement so one master key opens multiple locks, each operable by its own change key.
Question 2: A forensic locksmith examining a lock finds witness marks on the plug face consistent with a thin metal strip inserted above the keyway. This technique is best described as:
- Bumping
- Shimming
- Loiding (Correct answer)
- Impressioning
Correct answer: Loiding
Loiding (slip-knifing) involves inserting a thin strip between the door and frame to retract a spring latch, leaving characteristic marks on the plug face or latch.
Question 3: The Medeco biaxial cylinder differs from standard pin tumbler locks primarily because its driver pins:
- Are made of hardened steel to resist drilling
- Must rotate as well as elevate to the shear line (Correct answer)
- Are replaced by disc wafers for added security
- Use a sidebar that engages a secondary locking element
Correct answer: Must rotate as well as elevate to the shear line
Medeco biaxial cylinders require each key cut to both lift pins to the shear line AND rotate them to the correct angle, activating the sidebar.
Question 4: In forensic analysis, 'false shear line' evidence most directly indicates which picking method was used?
- Raking (Correct answer)
- Single-pin picking
- Bumping
- Decoding
Correct answer: Raking
Raking moves multiple pins simultaneously and often leaves evidence of false sets at the false shear line created by security pins.
Question 5: A Schlage B-series deadbolt uses a keyway designation stamped on the face of the plug. What forensic value does this marking provide?
- It reveals the bitting depth of the key
- It identifies the specific keyway to narrow key blank selection and ownership tracing (Correct answer)
- It indicates the lock's manufacturing date code
- It shows the master key bitting sequence
Correct answer: It identifies the specific keyway to narrow key blank selection and ownership tracing
The keyway designation identifies which key blank series fits the lock, aiding in tracing key blanks and reconstructing access history.
Question 6: Which characteristic of a key's bitting code is most useful when forensically comparing two keys suspected of being cut from the same original?
- Key length
- Bow shape
- Depth and spacing sequence (Correct answer)
- Blade thickness
Correct answer: Depth and spacing sequence
The depth and spacing sequence (bitting code) is the unique identifier that determines which locks a key will operate and is used for duplication comparison.
Question 7: An interchangeable core (IC) lock system, such as Best SFIC, is significant forensically because:
- The core cannot be removed without destroying evidence
- The core can be quickly swapped, making it difficult to establish a definitive access timeline (Correct answer)
- IC cores are immune to picking attacks
- The keyway is universal across all IC manufacturers
Correct answer: The core can be quickly swapped, making it difficult to establish a definitive access timeline
Because IC cores can be exchanged in seconds with a control key, establishing who had access during a specific period is more complex in forensic investigations.
CFL Lock Identification & Key Systems 2
Which key system feature allows a single master key to operate locks that each have their own individual change key?