In 1995, Aum Shinrikyo cult members released deadly sarin gas in Tokyo's subway. This unprecedented, random act of terror shook the world. How could such crimes happen? With that question still unanswered, the convicted Aum members and their leader Chizuo Matsumoto (aka Shoko Asahara) were finally executed last month. NHK had been exchanging letters with some of them. What do their last words tell us?