This.  He strikes me as the kind of "genius" who thinks he can defend himself, being so much smarter than everyone else and all, but I'd hope (for his own sake) that he isn't stupid enough to give them jack without something, in writing, for himself.  Cops can't give you shit, whatever they say verbally.  It needs to be the prosecutor, it needs to be in writing, and it needs a real criminal lawyer to look at it to make sure it isn't packed with "gotchas."  (Better call Saul!)