The Killian documents controversy (also referred to as Memogate or Rathergate) involved six documents containing false allegations about President George W. Bush's service in the Texas Air National Guard in 1972–73, allegedly typed in 1973. Dan Rather presented four of these documents as authentic in a 60 Minutes II broadcast aired by CBS on September 8, 2004, less than two months before the 2004 presidential election, but it was later found that CBS had failed to authenticate them. Several typewriter and typography experts soon concluded that they were forgeries. Lt. Col. Bill Burkett provided the documents to CBS, but he claims to have burned the originals after faxing them copies. CBS News producer Mary Mapes obtained the copied documents from Burkett, a former officer in the Texas Army National Guard, while pursuing a story about the George W. Bush military service controversy. Burkett claimed that Bush's commander Lieutenant Colonel Jerry B. Killian wrote them, which included criticisms of Bush's service in the Guard during the 1970s. In the 60 Minutes segment, Rather stated that the documents "were taken from Lieutenant Colonel Killian's personal files", and he falsely asserted that they had been authenticated by experts retained by CBS. The authenticity of the documents was challenged within hours on Internet forums and blogs, with questions initially focused on anachronisms in the typography, and the scandal quickly spread to the mass media. CBS and Rather defended the authenticity and usage of the documents for two weeks, but other news organizations continued to scrutinize the evidence, and USA Today obtained an independent analysis from outside experts. CBS finally repudiated the use of the documents on September 20, 2004. Rather stated, "if I knew then what I know now – I would not have gone ahead with the story as it was aired, and I certainly would not have used the documents in question", and CBS News President Andrew Heyward said, "Based on what we now know, CBS News cannot prove that the documents are authentic, which is the only acceptable journalistic standard to justify using them in the report. We should not have used them. That was a mistake, which we deeply regret." Several months later, a CBS-appointed panel led by Dick Thornburgh and Louis Boccardi criticized both the initial CBS news segment and CBS's "strident defense" during the aftermath. CBS fired producer Mapes, requested resignations from several senior news executives, and apologized