Sleuthic

The Black Files · November 13, 2026 · Difficulty: Investigator

Black File #155 — SolutionGrace Period

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The case

Floyd Okafor, landlord, was found dead at Ellery Court Apartments at 7:10 AM. Seven people were at the scene. Exactly one of them was alone with Floyd in the same zone.

The evidence (8 clues)
  1. Celia was standing on stairs.
  2. Blake was in Apartment 3B.
  3. David was standing on the floor.
  4. Amber was the southernmost person at the scene.
  5. David and Gail were in the same zone.
  6. Amber and Celia were in the same zone.
  7. Gail was the westernmost person at the scene.
  8. Eric was the northernmost person at the scene.

The answer

The killer: Eric Nakamura, alone with Floyd Okafor in the Laundry Room.

Fixing rows and columns from the extreme-position clues cascades through the board and leaves Eric alone with Floyd in the Laundry Room.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Amber: was the southernmost person of all, and since there is one person per row somebody occupies row 7: that is Amber; column C belongs to Celia; column A belongs to Gail; was in the same zone as Celia, and Celia can only be in the Hallway; column B already belongs to David. Only E7 is left.
  3. • Blake: was in Apartment 3B; column C belongs to Celia; row 1 belongs to Eric; row 4 already belongs to David; column E belongs to Amber; row 2 belongs to Gail. Only D3 is left.
  4. • Celia: was on the stairs; was in the same zone as Amber, and Amber can only be in the Hallway or the Laundry Room; row 7 belongs to Amber. Only C6 is left.
  5. • David: was standing on the floor; row 7 belongs to Amber; row 6 belongs to Celia; column C belongs to Celia; row 1 belongs to Eric; column A belongs to Gail; was in the same zone as Gail, and Gail can only be in the Lobby or the Hallway. Only B4 is left.
  6. • Eric: was the northernmost person of all, and since there is one person per row somebody occupies row 1: that is Eric; column C belongs to Celia; column A belongs to Gail; only Floyd and the killer were in the crime zone (the Laundry Room) and only Eric and Floyd can be there. Only F1 is left.
  7. • Floyd: row 7 belongs to Amber; row 6 belongs to Celia; column C belongs to Celia; row 1 belongs to Eric; column A belongs to Gail; Floyd cannot be in the Lobby: the crime zone holds exactly two people and David and Gail are already there, and with Floyd that would be more than two; Floyd cannot be in the Hallway: the crime zone holds exactly two people and Amber and Celia are already there, and with Floyd that would be more than two; row 4 already belongs to David; column E belongs to Amber; row 2 belongs to Gail; nobody else can occupy row 5, so it must be Floyd; nobody else can occupy column G, so it must be Floyd. Only G5 is left.
  8. • Gail: was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Gail; row 7 belongs to Amber; row 6 belongs to Celia; row 1 belongs to Eric; was in the same zone as David, and David can only be in the Lobby; row 4 already belongs to David. Only A2 is left.
  9. That already places Celia at C6, David at B4, Amber at E7, Blake at D3, Eric at F1, Floyd at G5 and Gail at A2.
  10. With all seven placed, the only people in the Laundry Room are Floyd and Eric: Eric was alone with the victim.
Solved map of Black File #155: Amber E7, Blake D3, Celia C6, David B4, Eric F1, Floyd G5, Gail A2
The solved map: Amber E7, Blake D3, Celia C6, David B4, Eric F1, Floyd G5, Gail A2.

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