Residents

**A**,

**B** and

**C**, each of whom are either a Liar or a Knight are brought to stand trial for a crime only one of them commited.

Each person accused one of the other two, but the records do not show who exactly. As it turned out, **A** was the only Knight of the three.

Curiously enough, if each person switched their testimony, and accused the remaining suspect (not themselves, and not who they accused originally), then **B** would come out to be the only Knight.

Who was the real culprit in the case?

(In reply to

answer by K Sengupta)

At the outset, in terjms of the first testimony, only A is the knight. By the given conditions, no individual accused himself, and accordingly it follows that A is not the guilty person, and he truthfully accused either B or C of being the culprit.

In terms of the proposed second testimony, B would be the knight. Then, B will truthfully accuse precisely one of A and C of being guilty. But, we have already established that A is not the culprit, and therefore it follows that B will truthfully accuse C of being the culprit.

Consequently, it follows that C is the guilty person.

*Edited on ***June 5, 2008, 1:11 pm**