9/11 wasn't the first attack that Rick Rescorla predicted.
The ex-military man and former police officer also predicted the 1993 bombing that saw Islamic terrorists drive a truck bomb into the unguarded basement of the World Trade Centre.
He'd warned the Port Authority in the years prior about the possibility of that exact scenario. Working in the building as corporate security for Dean Witter, who merged with Morgan Stanley Dean Witter & Co in 1997, he'd already investigated the security situation.
Watch: Bill Van Scoyoc was a Morgan Stanley employee working alongside Rescorla in the World Trade Center. Post continues after video.
But when he sounded his concerns, he was told by the Port Authority to "kiss off," his friend Dan Hill, who fought beside him in Vietnam, recalled to The New Yorker.
Afterwards he and Hill, who was trained in counter-terrorism, worked together to find the culprit and determined that it was likely planned by a radical imam at a mosque in either New York or New Jersey.
Subsequently, followers of Sheikh Omar Abdel Rahman, a radical Muslim cleric in Brooklyn, were eventually convicted.
Rescorla then turned his attention back to his office. Morgan Stanley Dean Witter & Co went on to occupy 22 floors of the South Tower and he was concerned the threat wasn't over. It was the tallest building in New York. It was in the heart of Wall Street. It was a symbol of America.
Together, Hill and Rescorla sketched their predictions of a new attack. They suspected an air attack by anti-American militants. Probably a cargo plan loaded with explosives or chemicals.
Rescorla tried to get Morgan Stanley Dean Witter & Co to move and build quarters in New Jersey instead. But the lease didn't expire until 2006 and even then they didn't heed his warning. So instead, Rescorla started working on an evacuation plan.
They practiced every three months. All 2700-odd employees would march down the emergency staircases two by two. Many would complain and argue about the need for the drills as they trekked down more than forty flights of stairs.