Here's the quote from John Kerry. It's in his biography by Doug Brinkley, Tour of Duty.
"I remember well April, 1968 - I was serving in Vietnam—a place of violence -- when the news reports brought home to me and my crewmates the violence back home - and the tragic news that one of the bullets flying that terrible spring took the life of that unabashedly maladjusted citizen."
John Kerry's timeline from his own website