First paragraph in the CBS release:
"The CBS News report was based on a preponderance of evidence: many interviews, both on- and off-camera, with individuals with direct and indirect knowledge of the situation, atmosphere and events of the period in question, as well as the procedures, character and thinking of Lt. Col. Killian, Lt. Bush's squadron commander in the Guard, at the time."
A preponderance of the evidence...many interviews...

Yet, they chose to go to air with 4 forged do ents and a liar. Wow!