Are we missing the point?

The whole controversy makes me wonder. In routine criminal and other investigations, interrogations (in the broadest sense) have to be recorded in order to help establish a factual foundation. Does the same standard apply here? If so, why is the C.I.A. seemingly afraid to document -- or keep whatever it has documented -- the evidence it draws out from detainees. Does it say more about the evidence than the tactics? Or not?