Honestly,jin could've record his convo with his dad when his dad was provoking him and telling him about his murders.Then he could use it as evidence.Manny also couldve done the same since jin's dad admitted to murdering the family ╮( ̄▽ ̄)╭
jin can't do that because he was scared of Kyun looking at her in a different light after finding out that he was also an accomplice. For manny I guess emotions got first than rational thinking
ALL HAIL WHATAFRUIT!! thank you for the update(づ ̄ ³ ̄)づ