In Madoff's case, he confessed to his sons. So again, this was a case of an insider having the goods, not the result of a speedy investigation.

Your timeline is correct, but once Madoff was confronted he just confessed and everything moved forward.

I mean yeah Madoff confessed and made the case open and shut.

SBF entered a Not Guilty plea but Ellison for all intents and purposes entered a Guilty plea on his behalf with her co-operation.

She also had no choice, as SBF was blaming her. The point being that they still didn't really need her help. It was obvious that he committed fraud, and there was plenty of proof of it.