CBS News announces that it now doubts the authenticity of the " Killian memos", after defending their authenticity for more than a week in the face of widespread expert opinion to the contrary. The network acknowledges that it was a mistake to use the memos as part of the supporting evidence in a 60 Minutes story by Dan Rather alleging deficiencies in U.S.PresidentGeorge W. Bush's Vietnam-era service in the Texas Air National Guard. (USA Today)