The Detective Reaper Invites

Would you like to play a game of deduction? Before you are the testimonies from the 3 suspects of a murder case. Among them is a lying murderer... X: Obviously, the culprit is Y. Y: I'm not the culprit. Z: X and I are not the culprit. Could you quickly tell who the murderer was? The job of a detective reaper is simple: get testimonies from the suspects, deduce the culprit, and execute them with your own two hands. Culprits always tell lies, and the innocent always tell the truth. If you choose incorrectly, you will be deemed unfit to be a detective reaper... and yours will be the next life to be harvested. This is a roguelite deduction adventure game. Every murder case you have to solve is randomly generated on a game board, and if you fail (and get a Game Over), you will have to start all over again. No two cases...