Matt Bevan

To understand how bad the data sharing was, think about information being like marbles in jars.

The FBI has a jar of marbles.

The CIA has one.

And the local police have one.

Each agency controls their own information, their own marbles.

Sharing marbles between them is incredibly complicated.

This whole system keeps things secure, but it means they basically can't work together.

And that problem was going to come into sharp focus for John O'Neill.

As he probed the World Trade Center attack of 1993, he became interested in one particular marble...

he believed the CIA had.

One that most counter-terrorism experts at the time weren't paying attention to.

In 1998, ABC America reporter Chris Isham, a personal friend of John O'Neill, trekked for 10 days across Pakistan to interview the leader of a little-known extremist group called al-Qaeda.

Osama bin Laden.

But Chris Isham and John O'Neill shared a growing interest in this old uncle in the Pakistani wilderness, who during the interview seemed pretty harmless.

Bin Laden's handlers wouldn't allow anyone to translate the Sheikh's answers.

It was only when the interview was finished and the producers sent the tapes back to be translated that they learned what this seemingly harmless man was saying.

Hmm, maybe not as harmless as he seems.

When he saw this interview, John O'Neill became fixated on Bin Laden.

He was sure that after a number of failed attacks on American sites, that the US was due for another domestic attack and that Osama Bin Laden would be the person to do it.

He tried hard to raise the alarm within the FBI, but because Bin Laden was an international threat, it was outside his remit.