I can't remember the name, but some did investigate all of those so called "solders" who testified, and wrote a book.
I'm not sure, but I think there is reference to it on the Swiftie's site. there is also Steve Pitkin? who swore an afidavit that he lied, Kerry was manipulating him.
Al Hubbard, a VVAW Executive Secretary at the time , claimed to have been an Air Force Captain wounded in Vietnam piloting a transport plane. In fact, Hubbard had been a staff sergeant who was not a pilot and who was never assigned to Vietnam. His was also one of the more fabulous detailed testimonies.
That book goes through each and everyone of those liars.
I'm looking for it now, but haven't found it yet.
"In Yesterday's Lies: Steve Pitkin and the Winter Soldiers, Scott Swett tells the story of a former VVAW member and participant in the Winter Soldier Investigation who has now filed an affidavit stating that John Kerry and others pressured him to give false testimony about American atrocities in Vietnam."
http://ice.he.net/~freepnet/kerry/staticpages/index.php?page=YesterdaysLies1