and windows, soot covering people's faces. >> before 9/11, there was another terrorist attack on the world trade center. the 1993 bombing claimed six lives that day, and a federal investigation would reveal 10 men had conspired to plan it. one of them was zach's father, sayyid. nearly three years before the bombing, he was put in prison following kahane's murder. but that didn't stop him from conspiring with the blind sheikh and others to bomb the twin towers. at trial, a federal grand jury charged sayyid with judicious conspiracy and under a federal racketeering law retried him for kahane's murder. he was found guilty and sentenced to life. >> when you did realize your father had a role in this thing you had seen on television, how did you feel? >> the first thing i thought was, there is no excuse for this. innocent people are killed.