I don't believe the person exists.
If they did, why not be out there telling the truth earlier when this was made a big issue?
Why wait till now to open their mouth?
As much as I like the Swift guys, this is not one that makes any sense.
If this person existed, they would have surfaced long ago IMO.
"If they did, why not be out there telling the truth earlier when this was made a big issue? "
From what I have heard (scuttlebutt only), this person did not want to come forward unless it was absolutely necessary.
Based on the closeness in the polls, it has become necessary.