Sleuthic

The Black Files · October 9, 2026 · Difficulty: Detective

Black File #120 — SolutionDelivery Window

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The case

Glen Hayes, warehouse manager, was found dead at Riverside Warehouse at 12:50 AM. Seven people were at the scene. Exactly one of them was alone with Glen in the same zone.

The evidence (9 clues)
  1. Alvin was sitting in a chair.
  2. Ethan was sitting on the sofa.
  3. Byron was standing on the floor.
  4. Byron and Felicia were in the same zone.
  5. Colin and Daniel were in the same zone.
  6. Alvin was the westernmost person at the scene.
  7. Colin was the easternmost person at the scene.
  8. Byron was the northernmost person at the scene.
  9. Daniel was the southernmost person at the scene.

The answer

The killer: Ethan Sato, alone with Glen Hayes in the Loading Dock.

Fixing rows and columns from the extreme-position clues cascades through the board and leaves Ethan alone with Glen in the Loading Dock.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Alvin: was sitting in a chair; was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Alvin. Only A2 is left.
  3. • Byron: was standing on the floor; was the northernmost person of all, and since there is one person per row somebody occupies row 1: that is Byron; column G belongs to Colin. Only E1 is left.
  4. • Colin: was the easternmost person of all, and since there is one person per column somebody occupies column G: that is Colin; row 1 belongs to Byron; row 7 belongs to Daniel; was in the same zone as Daniel, and Daniel can only be in the Loading Dock or the Main Aisle; row 6 belongs to Ethan; row 5 belongs to Glen. Only G4 is left.
  5. • Daniel: was the southernmost person of all, and since there is one person per row somebody occupies row 7: that is Daniel; column G belongs to Colin; was in the same zone as Colin, and Colin can only be in the Main Aisle. Only F7 is left.
  6. • Ethan: was sitting on the sofa; row 2 already belongs to Alvin; column A already belongs to Alvin; row 1 belongs to Byron; row 7 belongs to Daniel; column E already belongs to Byron; column F already belongs to Daniel. Only B6 is left.
  7. • Felicia: row 2 already belongs to Alvin; column A already belongs to Alvin; row 1 belongs to Byron; column G belongs to Colin; row 7 belongs to Daniel; was in the same zone as Byron, and Byron can only be in the Cold Storage; column B belongs to Ethan. Only C3 is left.
  8. • Glen: row 2 already belongs to Alvin; column A already belongs to Alvin; row 1 belongs to Byron; column G belongs to Colin; row 7 belongs to Daniel; Glen cannot be in the Main Aisle: the crime zone holds exactly two people and Colin and Daniel are already there, and with Glen that would be more than two; Glen cannot be in the Cold Storage: the crime zone holds exactly two people and Alvin, Byron and Felicia are already there, and with Glen that would be more than two; column E already belongs to Byron; column F already belongs to Daniel; row 6 belongs to Ethan; column B belongs to Ethan; row 3 belongs to Felicia; column C belongs to Felicia. Only D5 is left.
  9. That already places Alvin at A2, Byron at E1, Daniel at F7, Colin at G4, Ethan at B6, Felicia at C3 and Glen at D5.
  10. With all seven placed, the only people in the Loading Dock are Glen and Ethan: Ethan was alone with the victim.
Solved map of Black File #120: Alvin A2, Byron E1, Colin G4, Daniel F7, Ethan B6, Felicia C3, Glen D5
The solved map: Alvin A2, Byron E1, Colin G4, Daniel F7, Ethan B6, Felicia C3, Glen D5.

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