More than 21 years on from the horrific events of 9/11, one man is still wracked with guilt from his part of what happened that fateful day.
Vaughn Allex was working at the American Airlines check-in desk at Dulles International Airport in Virginia when he unknowingly checked in two terrorists onto Flight 77.
The pair were part of the group of five terrorists who later hijacked the plane and crashed it into the Pentagon, killing everyone on board and a further 125 people in the building, as part of the terrorist attacks of September 11, 2001.
