The Black Files · September 26, 2026 · Difficulty: Rookie
Black File #107 — SolutionDelivery Window
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The case
Denise Vaughn, auditor, was found dead at Riverside Warehouse at 8:40 PM. Seven people were at the scene. Exactly one of them was alone with Denise in the same zone.
The evidence (9 clues)
- Benjamin was standing on the stairs.
- Carl was in the Loading Dock.
- Angela was sitting on the sofa.
- Graham was in the Cold Storage.
- Floyd was standing on the floor.
- Eric was standing on the stairs.
- Floyd was the southernmost person at the scene.
- Benjamin was the westernmost person at the scene.
- Carl was the northernmost person at the scene.
The answer
The killer: Angela Nakamura, alone with Denise Vaughn in the Main Aisle.
Fixing rows and columns from the extreme-position clues cascades through the board and leaves Angela alone with Denise in the Main Aisle.
Step-by-step deduction
- Before placing anyone, each clue eliminates cells:
- • Angela: was sitting on the sofa; column A already belongs to Benjamin; row 1 belongs to Carl; row 6 belongs to Graham; only Denise and the killer were in the crime zone (the Main Aisle) and only Angela and Denise can be there. Only D2 is left.
- • Benjamin: was on the stairs; was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Benjamin. Only A5 is left.
- • Carl: was in the Loading Dock; was the northernmost person of all, and since there is one person per row somebody occupies row 1: that is Carl; nobody else can occupy column E, so it must be Carl. Only E1 is left.
- • Denise: Denise cannot be in the Cold Storage: the crime zone holds exactly two people and Benjamin and Graham are already there, and with Denise that would be more than two; row 5 already belongs to Benjamin; row 1 belongs to Carl; row 7 belongs to Floyd; row 6 belongs to Graham; column B belongs to Graham; nobody else can occupy column C, so it must be Denise. Only C4 is left.
- • Eric: was on the stairs; row 5 already belongs to Benjamin; row 1 belongs to Carl; row 7 belongs to Floyd; row 6 belongs to Graham; nobody else can occupy column G, so it must be Eric. Only G3 is left.
- • Floyd: was standing on the floor; was the southernmost person of all, and since there is one person per row somebody occupies row 7: that is Floyd; column B belongs to Graham. Only F7 is left.
- • Graham: was in the Cold Storage; row 5 already belongs to Benjamin; column A already belongs to Benjamin; row 1 belongs to Carl; row 7 belongs to Floyd. Only B6 is left.
- That already places Benjamin at A5, Angela at D2, Carl at E1, Denise at C4, Eric at G3, Floyd at F7 and Graham at B6.
- With all seven placed, the only people in the Main Aisle are Denise and Angela: Angela was alone with the victim.
