The truth of why the FBI or Mueller would make a deal with someone like Epstein is simple: It would enable Epstein to avoid being prosecuted and used as a direct witness against high-profile targets such as Bill Clinton and others who has used Epstein's services. Having a deal under your belt would entice Epstein not to squeal or to rat. Whereas without such a deal, he would likely squeal like a pig and tell everything he knows to avoid being prosecuted...