EXCLUSIVE: New Evidence Suggests Radical Cleric Anwar al-Awlaki Was an Overlooked Key Player in 9/11 Plot

Anteroom inside the Al- Ribat mosque in La Mesa, Calif. where Awlaki is believed to have met with two of the 9/11 hijackers. (FNC)

A year-long investigation by the Fox News' specials unit has uncovered new and overwhelming evidence that the American cleric, Anwar al-Awlaki, the first U.S. citizen on the CIA's kill or capture list, was an overlooked key player in the 9/11 plot.

In a new hour-long special, "Fox News Reporting: Secrets of 9/11," which debuts May 20 at 10 p.m. EDT, federal investigators go on the record for the first time about their painstaking work to investigate how Awlaki may have facilitated the hijackers in California and Virginia and possibly knew the details of the worst terrorist attack on U.S. soil.

Tune into "Fox News Reporting: Secrets of 9/11," which airs 10 p.m. Friday, 3 p.m. Saturday, 9 p.m Sunday and 12 a.m. Monday, ET.

"It was my feeling that they had to have a network," Criminal PENTTBOM (FBI's codename for the 9/11 case) investigator Jimmy Bush told Fox News in his first television interview.

"There was a mosque and the imam of that mosque was Anwar al-Awlaki, which raised my suspicions."

Former FBI Agent Bob Bukowski said the evidence strongly suggested Awlaki and his mosques on the East and West coasts were at the center of a network of helpers that enabled the hijackers to find apartments and obtain fake ids.

"The investigation at the time obviously was very suspicious," Bukowski said. "Knowing and proving are always two different things."

Fox News was told by multiple sources with first-hand knowledge of the 9/11 case -- including the former head of the joint congressional inquiry Sen. Bob Graham -- that the contact between Awlaki and hijackers Nawaf al-Hazmi and Khalid al-Mihdar and Hani Hanjour, three of the five hijackers who flew into the Pentagon, was not casual or coincidental but rather evidence of a purposeful relationship.

"There was a high probability that they (the hijackers) had shared with Awlaki what they were planning to do," Graham told Fox News. "The assumption was that it was a close relationship, and that Awlaki may have been one of the few, if not only people that Hazmi and Mihdhar had shared with, what they were there for and what the plot of 9/11 was going to be."

Graham told Fox News that a Saudi man, who has a few passing references in the 9/11 Commission Report, was hugely important to the joint Congressional inquiry because his story did not add up. Omar al-Bayoumi, 42, claimed to be a Saudi student in 2000, but Graham's team found no record to support his claims.

"He professed that he was a student. I checked through our committee with the university that he said he had attended. They had no record of his having been a student there," Graham said.

At the same time Bayoumi claimed to be a student, he was also collecting a salary as a ghost employee for Ercan, a subsidiary of a contractor for the Saudi Civil Aviation Authority.

The mysterious Bayoumi claimed that he met the two hijackers at random in a Middle Eastern restaurant after he had a meeting at the Saudi Consulate in Los Angeles in January 2000.

When asked how likely it was the chance meeting might occur, Graham said the Congressional inquiry hired a statistician to work out the odds.

"There were 134 Middle Eastern restaurants in Los Angeles in January of 2000. We had a statistician do a probability that four people would end up at the same place at the same time. And it was more than the 5 million to 1," Graham said.

Fox News reviewed hundreds of newly declassified documents to identify, for the first time, the network of helpers who allowed the hijackers to stay under the radar.

Bush, who spearheaded the phone records investigation out of New Jersey, found a direct link between Awlaki and Bayoumi's phone on the same day the hijackers moved into an apartment near the cleric's mosque in San Diego.

"There's a phone call from al-Bayoumi's cell phone to a phone listed to Anwar Awlaki in Denver, Colorado, the same day. The same day that al-Bayoumi says, 'I, uh, took 'em from there and I assisted them getting 'em, an apartment.' Now, what that phone call was or who that phone call was between, it's only speculation," Bush said.

But Bush added the connection could not be ignored. "But you can make a rational conclusion that there was contact at that time."

For the first time, Fox News reveals how those in the alleged 9/11 support network are still living in the U.S.

Asked if he believes the network of helpers is still here, Graham told Fox News that the network was never disrupted -- so there is every reason to believe it remains in place.

"I have no reason to believe it's not."

National Correspondent Catherine Herridge's first book "The Next Wave: On the Hunt for al Qaeda's American Recruits" will be published by Crown on June 21st. It draws on her reporting for Fox News into al-Awlaki and his new generation of recruits – al Qaeda 2.0. New evidence shows the cleric was an overlooked key player in the 9/11 attacks who double crossed federal investigators.