Four Statements

The case file

A silver watch vanished from the evidence locker. Four people with access were questioned, and each made exactly one statement. Who took the silver watch?

The rule: Exactly 1 of the four statements is true. The other 3 are false.

The clues

1. Derek Sloane said, "I didn't take it."
2. Dana Wren said, "Lucy Fern took it."
3. Silas Reed said, "Lucy Fern took it."
4. Lucy Fern said, "I didn't take it."

Who did it?

1. Derek Sloane
2. Silas Reed
3. Lucy Fern
4. Dana Wren

The verdict

Derek Sloane

Only Derek Sloane fits -- then exactly 1 of the four statements are true (Lucy Fern's statement). Not Silas Reed: if Silas Reed had taken the silver watch, 2 of the four statements would be true -- but exactly 1 are. Not Lucy Fern: if Lucy Fern had taken the silver watch, 3 of the four statements would be true -- but exactly 1 are. Not Dana Wren: if Dana Wren had taken the silver watch, 2 of the four statements would be true -- but exactly 1 are.