he did lie about it - well known he shredded all the evidence.
Not just that, but according to someone who was trying to work to get POW records regarding WW2 and Vietnam through Poland, Kerry did nothing to get the massive files available to them. The files in Poland were also subsequently destroyed. I don't want to wrongly state the record on that, but NavyChief from the Swiftvets board was there at the time and submitted quite an expose on what happened. It was posted here too.
Tonkin probably has that link available.