Barry Ritholtz over at the The Big Picture has one amazing post that is a must read.
In Why a Madoff Deal Might Take Place he links and implies:
Hence, the possible Madoff deal. One theory floating around is that Madoff will implicate the major banks (HSBC, RBS, Santander, BNP Paribas, Nomura), fund of funds, referrers in his massive fraud. Once he rolls over and sings, alleging they knew (or should have known) it clears the path for a massive litigation frenzy against any and all of the parties involved.