Key & Lock Examination Flashcards

Which microscopic feature BEST distinguishes a key cut made by a code-cutting machine from one made by duplicating a key?

Answer: Cutter wheel radius marks specific to code machines

Code-cutting machines use specific cutter wheel geometries that leave characteristic radius marks in the valley of cuts, which differ from profile-following duplicating machine marks.

In wafer tumbler locks, what forensic indicator would suggest manipulation rather than the correct key was used?

Answer: Asymmetric wear or scoring on individual wafers

Picks or false keys contact wafers at unpredictable angles, causing asymmetric scoring or wear that differs from the uniform edge contact produced by a correct key.

A forensic locksmith is asked to determine if a high-security lock with sidebars was bypassed. Which examination is MOST probative?

Answer: Inspecting the sidebar channels and rotating element for manipulation marks

Sidebar mechanisms leave distinctive marks on the rotating elements and channels when manipulated, as tools must interact with an additional layer of locking components.

What is the forensic significance of finding lubricant (graphite or oil) inside a lock that was reportedly never maintained?

Answer: It may indicate a third party accessed or tampered with the lock interior

Unexpected lubricant inside a lock that was never serviced may indicate unauthorized access or manipulation, since lubricants are often used to aid picking or bypass techniques.

When documenting key evidence, a CFL should record the key's 'cuts per inch' (CPI) because it:

Answer: Establishes the key's cut spacing standard, linking it to a specific lock family

CPI (cuts per inch) is a standard measurement that defines the spacing of bitting positions, which is unique to each manufacturer's lock family and helps link a key to a specific product line.

A tubular lock examined by a CFL shows radial scratches symmetrically arranged around the plug face. This pattern is MOST consistent with:

Answer: A tubular lock pick or impressioning tool attack

Tubular lock picks and impressioning tools contact all pins simultaneously around the plug face, leaving symmetrical radial scratches unique to attacks on tubular locks.

What does 'decoding' a lock mean in forensic locksmith terminology?

Answer: Determining the existing key bitting combination without disassembly

Decoding means determining the current key bitting (combination) of a lock through inspection or manipulation, without necessarily disassembling it.