S.O.P.
The Left's objective in the investigation is to keep investigating until they get the answer they are looking for, i.e., something that will wreck the Bush presidency. If nothing has come up so far, then by their definition the investigation is not "complete," and "questions remain."
For example, since they found nothing in the "AWOL" investigation, then by their definition there has not been enough information released.
This is very similar to the concept of recounting and reinterpreting votes over and over again until your candidate wins. Then stop.