...an attorney on the "fruit from the poisoned tree" line of reasoning on the indictments. In other words, if the investigation/prosecution were corruptly motivated, if not also corrupt in execution, then can anything that comes from it be considered illegitimate and tossed.

It could be (and, I guess, is being) argued, for example, that Willis pursued the investigation/prosecution simply for her own personal gain. Given the strong protections afforded defendants in our system, this seems likely to me, and, in fact, it's an ask of the defendant who filed this claim against Willis -- to have the charges dismissed.

A second question for you would be how easy would it be for another prosecutor simply to step into Willis' shoes and pursue the same case? One would think if that her investigation/prosecution is corrupted, and her entire office likely participated in some form with that investigation, then everyone in that office is tainted, so who'd be left to prosecute it?