Solution: The Unfinished Map at the Museum

The clues

• 
  DarioThe jazz musician.

  He was in the fifth row.

• 
  OscarThe antiques dealer.

  He was beside a chair.

• 
  SofiaThe chess prodigy.

  She was in the third column from the left.

• 
  LenaThe painter who never finishes a canvas.

  She was beside a rug.

• 
  Karim · VictimThe family lawyer.

  The victim. He was alone with the killer. He was in the Cloakroom with another man.

• 
  HugoThe retired colonel.

  He was in the third row.

Step by step

The order our solver finds. Each step uses only the clues and what the steps before it proved, and its heading links to the technique.

1. Pinned suspects Dario can only be in the fifth row, so nobody else can be there.
2. Pinned suspects Hugo can only be in the third row, so nobody else can be there.
3. Pinned suspects Lena can only be in the second row, so nobody else can be there.
4. Pinned suspects Sofia can only be in the third column from the left, so nobody else can be there. Placed: Lena: row 2, column 2 (Courtyard).
5. The only one who fits Only Hugo can still reach the fifth column from the left, so he must be there. Placed: Hugo: row 3, column 5 (Lobby).
6. The only one who fits Only Karim can still reach the fourth column from the left, so he must be there.
7. Room counting The victim, Karim, cannot be in the highlighted cells: his room there could not hold exactly one other person. The cells meant: row 1, column 4. Placed: Karim: row 4, column 4 (Cloakroom).
8. Room counting Karim was in the Cloakroom with exactly one other man. Only Oscar can still get there. Placed: Oscar: row 1, column 1 (Cloakroom); Dario: row 5, column 6 (Lobby); Sofia: row 6, column 3 (Café).