The answers lie only in the unique circumstances of each case and in the strategies that counsel employs. Even institutional clients are usually personified by a human being on whom lawyers can rely to learn the basic facts of the case, the identity of witnesses to be interviewed and the perceived outlines of the wrong to be redressed. Funds may be missing, assets may suddenly prove worthless but typically it is not at all clear how or why this has happened. The sophisticated, modern embezzler usually covers his or her tracks in a maze of transactions and entities that confound easy analysis. There often is no one to ask to clarify the multitude of transactions and paper trail.
Obfuscation is an important technique in creating the fraud in the first place.
From the defense perspective, the lawyers demand that answers to interrogatories or that party deponents explain the basis of the claims. You have accused my client of fraud and I want to know why. In response, plaintiff's counsel calmly and coyly observes that no one knows anything other than what they have learned from advice of counsel and that, of course, is privileged or work product. But the defense may have the last laugh. The plaintiff may get away with keeping the adversary at bay in discovery, but counsel can't be coy at trial.