Sleuthic

The Black Files · October 30, 2026 · Difficulty: Cadet

Black File #141 — SolutionThe Last Witness

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The case

Erica Brennan, visiting sister, was found dead at Ellery Court Apartments at 7:10 AM. Seven people were at the scene. Exactly one of them was alone with Erica in the same zone.

The evidence (11 clues)
  1. Erica was standing on the floor.
  2. Gina was standing on stairs.
  3. Benjamin was standing on stairs.
  4. Fiona was standing on the floor.
  5. Anita was standing on the floor.
  6. Fiona was in the Hallway.
  7. Gina was in the Laundry Room.
  8. Daniel was standing on stairs.
  9. Cynthia was the northernmost person at the scene.
  10. Daniel was the westernmost person at the scene.
  11. Erica was the easternmost person at the scene.

The answer

The killer: Anita Kim, alone with Erica Brennan in the Lobby.

Fixing rows and columns from the extreme-position clues cascades through the board and leaves Anita alone with Erica in the Lobby.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Anita: was standing on the floor; row 3 already belongs to Erica; row 7 already belongs to Gina; column E already belongs to Gina; row 1 belongs to Cynthia; nobody else can occupy row 4, so it must be Anita. Only F4 is left.
  3. • Benjamin: was on the stairs; row 3 already belongs to Erica; row 7 already belongs to Gina; column E already belongs to Gina; row 1 belongs to Cynthia; column A belongs to Daniel; only Erica and the killer were in the crime zone (the Lobby), and those are already Anita and Erica. Only D5 is left.
  4. • Cynthia: was the northernmost person of all, and since there is one person per row somebody occupies row 1: that is Cynthia; column G already belongs to Erica; column E already belongs to Gina; column A belongs to Daniel; only Erica and the killer were in the crime zone (the Lobby), and those are already Anita and Erica; column D already belongs to Benjamin; column C belongs to Fiona. Only B1 is left.
  5. • Daniel: was on the stairs; was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Daniel; row 6 belongs to Fiona. Only A2 is left.
  6. • Erica: was standing on the floor; was the easternmost person of all, and since there is one person per column somebody occupies column G: that is Erica. Only G3 is left.
  7. • Fiona: was standing on the floor; was in the Hallway; row 3 already belongs to Erica; row 7 already belongs to Gina; row 5 already belongs to Benjamin. Only C6 is left.
  8. • Gina: was on the stairs; was in the Laundry Room. Only E7 is left.
  9. That already places Erica at G3, Gina at E7, Anita at F4, Benjamin at D5, Cynthia at B1, Daniel at A2 and Fiona at C6.
  10. With all seven placed, the only people in the Lobby are Erica and Anita: Anita was alone with the victim.
Solved map of Black File #141: Anita F4, Benjamin D5, Cynthia B1, Daniel A2, Erica G3, Fiona C6, Gina E7
The solved map: Anita F4, Benjamin D5, Cynthia B1, Daniel A2, Erica G3, Fiona C6, Gina E7.

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