As I recall, one of the key actual "vets" touted by Kerry during this "Winter Soldier" business last year recanted everything he said in 1970 about the supposed "atrocities" he'd witnessed in Vietnam and said he'd been haunted by his well-publicized lies (pushed into it by Kerry and his allies in the left movement) ever since. At least he was an actual veteran of the war, and not like the bozo/jerk whom Kerry supported who had NEVER SERVED in Vietnam yet claimed he witnessed all sorts of horrible things there in Winter Soldier testimony and in an appearance before Scuba Kennedy in Congress.
You're thinking of Steve Pitkin, whose story and affidavit were published by WinterSoldier.com in September 2004.