The Missing Key

The case file

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

The rule: Exactly 2 of the four statements are true. The other 2 are false.

The clues

1. Lena Brooks said, "I didn't take it."
2. Ava Lindt said, "I took it."
3. Hugo Bain said, "Ava Lindt took it."
4. Theo Marsh said, "I took it."

Who did it?

1. Theo Marsh
2. Lena Brooks
3. Ava Lindt
4. Hugo Bain

The verdict

Theo Marsh

Only Theo Marsh fits -- then exactly 2 of the four statements are true (Lena Brooks's statement; Theo Marsh's statement). Not Lena Brooks: if Lena Brooks had taken the glass paperweight, 0 of the four statements would be true -- but exactly 2 are. Not Ava Lindt: if Ava Lindt had taken the glass paperweight, 3 of the four statements would be true -- but exactly 2 are. Not Hugo Bain: if Hugo Bain had taken the glass paperweight, 1 of the four statements would be true -- but exactly 2 are.