Are we sure about this - that he was never the vice chairperson? I'm always wary of things that sound too good to be true (but always hopeful)!
I've been researching the heck out of it, and can't see any reference to him being Vice Chairman of THAT committee.
He was Vice-Chairman of a Select Committee on POWs and MIAs, so I'm sure his crack staff (pun intended) sorta blended the Kerry Kerrey Select Committee thing.