Good-for-nothing Prosecutor

Logic Level 2

Three men X, Y, and Z were tried for breaking and entering. It is known that the prosecuting attorney either always lies or always tell the truth. He made the following statements in court:

(1) X is not guilty.
(2) Either Y or Z are guilty.
(3) Z is guilty.

If there can only be one person who is guilty, can you determine who is definitely not guilty?

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