Burkett is the perp. He IS the future convicted forger/felon. I am just guessing but I think how he could have gotten to CBS is through Michael Moore. That would be a possible scenario cause if I am correct Burkett was a source for Michael Moore's film. Since Burkett can't get the DNC to pay attention to him he calls Michael Moore who he knows through the film. Moore who will believe anything about Bush, then calls Rather's office. They would certainly be willing to talk to a fellow Bush hater. Hence Rather's stonewalling. To admit the evidence is forgery means he must reveal his source for the documents which would include Michael Moore. This would discredit Moore and his film and hurt Kerry's campaign.
Just a little speculation. There has to be something Rather is hiding about his source. That's the next big angle in this story.
More from Burkett in 2003:
http://www.veteransforpeace.org/what_do_you_say_032203.htm
"I had been 'loaned' from the senior staff and state planning officer of the Texas National Guard to the Department of the Army for a series of these special projects after angering George W. Bush by refusing to falsify readiness information and reports; confronting a fraudulent funding scheme which kept 'ghost' soldiers on the books for additional funding, and refusing to alter official personnel records [of George W. Bush]. George W. Bush and his lieutenants were mad."