Officer Yamaato is clear in the eyes of the law for purposes of that criminal case, but he can still be sued civilly and have to prove his lack of culpability again, but in a civil case with its lower bar of proof for the plaintiffs  

Additionally, the entire paper trail is fair game for impeaching his testimony in other cases he may be a party or witness to.  Which makes a good reason to remove ethically challenged officers.

Lastly, it may be morally correct to have these prior potentially bad acts be reintroduced because any long time legal observer can tell you that courts are not finders of truth, but rather fairly imperfect resolvers of disputes.  So I would be very hesitant to assume that a DANC plea at all accurately determines any real finding of ethical short comings whatsoever.