Sleuthic

The Black Files · September 30, 2026 · Difficulty: Rookie

Black File #111 — SolutionOvertime

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The case

Carla Booker, nurse, was found dead at Lakeside Clinic at 10:45 PM. Seven people were at the scene. Exactly one of them was alone with Carla in the same zone.

The evidence (9 clues)
  1. Edgar was sitting on the sofa.
  2. Felicia was in the Waiting Room.
  3. Deborah was standing on the stairs.
  4. Gwen was standing on the stairs.
  5. Alicia was standing on the stairs.
  6. Felicia was sitting on the sofa.
  7. Brian was the westernmost person at the scene.
  8. Alicia and Deborah were in the same zone.
  9. Alicia was the easternmost person at the scene.

The answer

The killer: Gwen Adebayo, alone with Carla Booker in the Staff Lounge.

Fixing rows and columns from the extreme-position clues cascades through the board and leaves Gwen alone with Carla in the Staff Lounge.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Alicia: was on the stairs; was the easternmost person of all, and since there is one person per column somebody occupies column G: that is Alicia; was in the same zone as Deborah, and Deborah can only be in Exam Room 2 or the Staff Lounge. Only G1 is left.
  3. • Brian: was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Brian; row 1 already belongs to Alicia; row 4 belongs to Felicia; row 3 already belongs to Deborah; row 7 already belongs to Edgar; row 5 already belongs to Gwen. Only A2 is left.
  4. • Carla: Carla cannot be in the Waiting Room: the crime zone holds exactly two people and Brian and Felicia are already there, and with Carla that would be more than two; column G belongs to Alicia; column B belongs to Felicia; nobody else can occupy row 6, so it must be Carla; nobody else can occupy column D, so it must be Carla. Only D6 is left.
  5. • Deborah: was on the stairs; column G belongs to Alicia; column A belongs to Brian; was in the same zone as Alicia, and Alicia can only be in Exam Room 2; row 1 already belongs to Alicia; nobody else can occupy column F, so it must be Deborah. Only F3 is left.
  6. • Edgar: was sitting on the sofa; column G belongs to Alicia; column A belongs to Brian; column B belongs to Felicia; row 4 belongs to Felicia. Only E7 is left.
  7. • Felicia: was in the Waiting Room; was sitting on the sofa; column A belongs to Brian; row 1 already belongs to Alicia. Only B4 is left.
  8. • Gwen: was on the stairs; column G belongs to Alicia; column A belongs to Brian; row 1 already belongs to Alicia; nobody else can occupy column C, so it must be Gwen. Only C5 is left.
  9. That already places Alicia at G1, Carla at D6, Deborah at F3, Edgar at E7, Felicia at B4, Gwen at C5 and Brian at A2.
  10. With all seven placed, the only people in the Staff Lounge are Carla and Gwen: Gwen was alone with the victim.
Solved map of Black File #111: Alicia G1, Brian A2, Carla D6, Deborah F3, Edgar E7, Felicia B4, Gwen C5
The solved map: Alicia G1, Brian A2, Carla D6, Deborah F3, Edgar E7, Felicia B4, Gwen C5.

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