Instead of having the second killer of a trial get off scot-free, the remaining students have to choose who gets executed.

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Instead of having the second killer of a trial get off scot-free, the remaining students have to choose who gets executed.
Character 1 likes Character 2. Maybe the feeling is mutual, maybe it is one-sided.
Character 2 poisons a meal and tells Character 1 to give it to Character 3 who eats it and dies. During the trial, the students are unsure who to vote guilty and the mascot says that either one is fine.
Wanting to save Character 2, Character 1 acts unlikable and says that they intentionally killed the victim, causing the others to vote them.
After the trial, the mascot reveals that no, this was in fact Character 2's fault and now the others have doomed Character 1 to death.
Obviously the class is guilty and hate Character 2 now. Maybe this causes a redemption for Character 2, or maybe they have no remorse.