prosecutors. this is coming out now. it occurred in the fall, a period when prosecutors spoke to other white house heavyweights including john kelly. reports are mueller's team may be interested in what sanders knew about the trump tower cover-up story and if what she told the public may differ from what she says when she is effectively under oath. i am joined by someone who is really perfect to discuss all of this with, john carlin was chief of staff to bob mueller. i'm also joined by former federal prosecutor gene rosy and melissa murray, a law professor at nyu. thanks to each of you. on the mueller piece, each of you are legal experts in various ways, but on the mueller piece, john, what would bob mueller want to know from this person who plays a spokesperson role? would she have the juice on anything else? >> well, i think you need to ask and expect them to thoroughly and diligently investigate the facts as they have to ask her,