The story of 9/11 is filled with painful “what-ifs.” Among the most prominent:

• What if the CIA hadn’t blocked two FBI agents from alerting Bureau headquarters that a future 9/11 hijacker had obtained a multi-entry U.S. visa?
• What if the FBI hadn’t nixed agents’ request for a warrant to search the computer of “20th hijacker” Zacharias Moussaoui after his arrest in August 2001?
• What if the FBI hadn’t ignored a Phoenix agent’s July 2001 recommendation to contact aviation colleges across the country, on suspicion that Osama bin Laden was preparing extremists to “conduct terror activity against civilian aviation targets”?

Those what-ifs give us all pause, but they weigh heaviest on those who were closest to them, such as retired FBI counterterrorism agent Ken Williams, author of the so-called “Phoenix memo.”

Though his unheeded warning about extremists at flight schools looms large in the saga of 9/11, Williams is haunted by two more what-ifs that are lesser-known but equally gut-wrenching:

• What if his request for a surveillance team to monitor bin Laden disciples at an Arizona aviation school hadn’t been declined in favor of the FBI’s pursuit of drug smugglers?
• What if he hadn’t been ordered to suspend his investigation of those extremists for several months to help with an arson case?

For Williams, the answer is all too clear: His investigation would have led to the scrutiny of two future 9/11 hijackers—and that scrutiny may have started unraveling the entire plot.

Extremists at Embry-Riddle

In April 2000, Williams received an important tip from a confidential informant who’d once been a member of a Middle Eastern terrorist organization.

The informant had built a stellar reputation for providing valuable information. “I used to refer to him as my E.F. Hutton,” says Williams. “When he spoke, you listened.”

The informant told Williams that two foreign students were attempting to recruit Phoenix-area Muslims to an organization called Al-Muhajiroun, or “The Emigrants.”

Founded in Saudi Arabia and then banned by the kingdom in 1986, Al-Muhajiroun was unabashedly extremist. Before 9/11, the group referred to itself as “the eyes, the ears and the mouth of Osama bin Laden,” says Williams.

In 1998, the group’s leader issued a fatwa, or religious decree, declaring jihad against the U.S. and British governments and their interests—including airports. After 9/11, Al-Muhajiroun became notorious for organizing a “magnificent 19” conference in London in honor of 9/11’s 19 hijackers.

The informant gave Williams one of the flyers the pair had been using in their recruiting drive. The phone number on the flyer belonged to Lebanese student Zakaria Soubra. Via surveillance of Soubra, Williams and his team identified his counterpart as a Saudi named Ghassan al-Sharbi.

Both were students at Embry-Riddle Aeronautical University in Prescott, Arizona. Williams describes it as a prestigious school providing an “Ivy League” education in aviation and related sciences.

Soubra was studying aviation security, while al-Sharbi studied engineering. The two were also making frequent, two-and-a-half-hour drives to Phoenix to recruit new members of Al-Muhajiroun from area mosques.

Williams and another agent traveled to Prescott to interview them at the small room they shared at a cheap motor lodge. Williams quickly noticed it was decorated with photos of Osama bin Laden, Ibn al-Khattab of the Arab Mujahideen in Chechnya, and wounded mujahideen fighters.

In his years of experience, Williams had grown accustomed to Middle Eastern students being “meek, mild and intimidated as shit when you show up at their door”—the product of growing up in countries with iron-fisted security forces. Soubra, however, was a jarring exception.

“He told me he considered the FBI, the United States military and the United States government legitimate military targets of Islam, and he described bin Laden as a great Muslim brother,” says Williams. “He was raising his voice, and you could see the veins on the side of his temples start to pop out of his head.”

“Trust me, I did everything in my power to get him to assault me or my partner…try to push us or do something so we could arrest him for assault on a federal officer,” says Williams.

On the way out, he told them, “We know what you’re all about and we’re not going away. If you cross that line, you will go to jail. We’ll find you wherever you’re at.”

“I don’t generally don’t make those kind of threats, because they’re idle, but I wanted to kind of up-it a notch with them,” says Williams.

Links to a Possible 9/11 “Dry Run”

Williams discovered that Soubra and al-Sharbi were driving a car registered to Muhammad al-Qudhaieen, a Saudi student living three hours away at the University of Arizona.

Months earlier, in November 1999, al-Qudhaieen and Hamdan al-Shalawi, a Saudi attending Arizona State, were involved in an incident that prompted an America West flight to Washington, D.C. to make an emergency landing in Columbus, Ohio.

Crew members said the two had asked a variety of suspicious technical questions, and that al-Qudhaieen twice attempted to open the cockpit door. He told investigators in Columbus he’d mistaken it for the bathroom door.

Noting that these were students at a top-notch university with experience traveling internationally, Williams says he finds the excuse ridiculous.

“They were conducting an intelligence-collecting operation on board the aircraft, to see how the flight crew was going to react and see how far away they could get with doing things,” he says.

The America West incident has been cited in ongoing civil litigation in which 9/11 families, survivors and insurers allege various Saudi officials helped facilitate the al Qaeda plot. Al-Qudhaieen and al-Shalawi were traveling at Saudi expense to an event at the Saudi embassy.

The pair were released after questioning. Immediately after the incident, Williams says, they held a press conference in Washington and claimed to have been victims of Islamophobia.

Williams says the public relations move was likely part of al Qaeda’s strategy: Well-publicized, embarrassing accusations of bigotry against America West would make other airline and airport employees reluctant to react to future suspicious behavior.

Al-Qudhaieen and al-Shalawi’s profession of innocence was undermined in November 2000, when the FBI received reports that al-Shalawi trained in Afghanistan to conduct attacks like the 1996 bombing of the Khobar Towers housing facility in Saudi Arabia, which killed 19 American service members and injured hundreds.

After being questioned by Williams, Al-Sharbi fled the United States. In the wake of 9/11, he was arrested in Pakistan with Abu Zubaydah, who was then one of the world’s most-hunted al Qaeda associates.

Add it all up and Williams was clearly onto something big in the year 2000.

However, since his investigation subjects hadn’t committed any overt criminal acts, building a case would require a lot of work, with an emphasis on visual surveillance—tracking comings and goings, identifying associates by photographing them and checking their license plates, noting places subjects and their associates routinely visit.

It’s a highly labor-intensive undertaking. In the FBI, doing it well means calling in the agents of the Special Operations Group (SOG).

“Surveillance is the only thing these agents do,” says Williams. “They’re given extensive training on the tradecraft of whatever enemy they’re looking at…(including) how al Qaeda functions. They study whatever we have in our intelligence quivers so they know what to look for when they’re out there,” says Williams.

“Every agent can do some surveillance,” he continues, “but these guys have old beater automobiles, they have aircraft capabilities, electronic capabilities, photographic capabilities—video and still—and they’re trained how to use all this stuff.” Their observations are summarized in a daily report provided to the lead agent on the case.

However, none of that would be available to Williams: Despite the disturbing set of facts and associations he’d uncovered, his request for SOG support was denied.

Chalk it up to a warped set of institutional priorities: In the pre-9/11 FBI, counterterrorism often took a back seat to drug investigations.

“I’ve got this threat I’ve identified through my training and expertise. I’m telling my command staff ‘these guys are the real deal, this is no bullshit,’ yet (my bosses are) still held accountable to meeting what headquarters has set as priorities for the southwest border states—and that’s drug interdiction and that’s taking down cartel members,” says Williams.

Williams says he doesn’t blame his Phoenix supervisors, because they were following priorities dictated in Washington. He does, however, resent that the FBI had to pursue drug cases at all.

“What angers me about it and what I get upset about is—that’s what the whole Drug Enforcement Administration was created to counter. We were the only agency at that time that protected the United States from terrorists. You’ve got the DEA, every police agency and their mother looking at drugs. Why can’t the FBI get out of the drug trafficking arena and concentrate on protecting the national security of the United States of America in the areas where we have the sole purview to do it? If we don’t do it, nobody’s doing it at that time,” Williams says.

America’s powerful post-9/11 marijuana legalization trend makes the de-prioritization of his counterterrorism case all the more aggravating in retrospect.

“Some of the stuff we were competing with were marijuana smuggling cases. Now, for chrissakes, every other corner out here has a marijuana dispensary. They’re as frequent as Starbucks,” says Williams.

Denied SOG support, Williams and his teammates soldiered on without it, conducting their own off-and-on surveillance as best they could.

“I was doing it haphazardly. I was doing it by myself and maybe with a couple squad mates,” says Williams. “But there’s a huge degree of difference between having an SOG team on a target and a group of non-SOG-trained agents who do it part-time at best.”

Even in well-resourced situations, pursuing such a case can take a lot of time. “Some people think 12 months in an investigation is a long time—not when you’re working these kinds of cases like Soubra and Al Sharbi,” says Williams.

Collecting intelligence, trying to recruit informants, and amassing the information needed to obtain more investigative authority is a slow grind. The lack of SOG support made it all the more difficult.

The prioritization of drug cases was a major drag on Williams’ investigation, but things were about to come to a screeching halt.

An Arsonist Unwittingly Abets al Qaeda

In December 2000, someone started setting fire to million-dollar houses under construction along the border of the Phoenix Mountains Preserve. One of them was even burned twice. Eleven structures were torched in all.

The media speculated that the arson was the work of an eco-terrorist organization—perhaps the Earth Liberation Front or something akin to it. In messages at the crime scenes and elsewhere, the perpetrator started identifying as the “Coalition to Save the Preserves,” and seemed to revel in taunting police.

The arson spree was racking up millions of dollars in damage and commanding high media attention. Between public pressure amid mounting concerns the fires could take a deadly turn, Phoenix police asked the FBI for help.

Williams received a profoundly unwelcome order: He and every member of the Phoenix counterterrorism squad would have to shelve their current investigations and pursue the arson case full-time.

“I went to my supervisor at the time, Bill Kurtz, and I said, ‘Bill, you can’t take me off this case. This is the real deal…these guys are with this al Qaeda group that we’re starting to learn about, that blew up the U.S. embassies in Kenya and Tanzania’.”

The decision stood. And the timing couldn’t have been worse.

The very month Williams was forced to turn his eyes away from Arizona’s network of al Qaeda sympathizers, Hani Hanjour and Nawaf al-Hazmi moved from Southern California to Phoenix.

Nine months later, they would hijack American Airlines Flight 77. Hanjour himself would steer the Boeing 757 into the Pentagon.

Williams is confident that, had he not been diverted to the arson case, Hanjour and al-Hazmi would have come under his scrutiny: “There’s no question in my mind. I’m convinced we would have crossed paths with them. Guarantee you.”

“All these guys were in the same circle. We got the two guys on America West Airlines doing their dry run and collecting intel. We’ve got Ghassan al-Sharbi who was arrested with Abu Zubayda, so he was kind of a big shot. And then we’ve got these two guys getting ready to kill themselves on September 11th coming into our area. All these guys are living within miles of each other. They would’ve been bouncing off each other, I guarantee,” he says.

Williams did help solve the arson spree, which turned out to be the work of a lone, thrill-seeking arsonist named Mark Warren Sands, who was indicted on June 14, 2001.

By that time, Hanjour and al-Hazmi had left Arizona, arriving in Falls Church, Virginia in April.

Williams gives his former supervisor Kurtz full credit for expressing regret to the 9/11 Commission about having taken Williams off the terror case.

He holds lingering anger, however, for the arsonist who put Kurtz in a tough position.

“I wish I could prosecute him for something tied to 9/11, because he really took our eyes off the guys in Prescott,” says Williams.

With the arson case closed, Williams ramped his counterterrorism investigation back up, posting his now-famous “Phoenix memo” on July 10.

With his investigation first slowed by a lack of surveillance assets and then halted for months by the arson investigation, his recommendation for a nationwide FBI campaign to contact civil aviation universities and colleges in search of extremist students was submitted just two months before 9/11—and then ignored until it was too late.

A Reunion with al-Sharbi

Having been arrested in Pakistan with Abu Zubaydah, Ghassan al-Sharbi—the quieter of Williams’ two Prescott investigation targets—is now detainee #682 at Guantanamo Bay, Cuba. A 2016 government profile said “he has been mostly non-compliant and hostile with the guards…his behavior and statements indicate that he retains extremist views.”

You’ll recall that Williams closed his Prescott interview of al-Sharbi with a warning: “If you cross that line, you will go to jail. We’ll find you wherever you’re at.” Little did Williams know it would happen halfway around the world.

After al-Sharbi was captured, Williams traveled to Gitmo to question him. When Williams entered the room, he says al-Sharbi’s face signaled his recognition—with an expression that said, “Oh, shit.”

Williams greeted him by saying, “I told you we’d find you.”

Recalling the scene with a chuckle, Williams says, “It was a Hollywood moment. You couldn’t script it any better.”

A New Focus: Making a Case Against Saudi Arabia

While that moment gave Williams something to smile about, 9/11 remains a constant and grim presence in his life.

There’s no escaping the nagging question of how the world may be different had he received the surveillance support he’d requested, or if he hadn’t been reassigned to the arson case.

“I what-if that every day of my life and I will til the day I die,” he says. “How close were we?”

“My ex-wife used to say I was obsessed with it, but I’d say, ‘Well, how can you not be obsessed with it? There’s thousands of people dead and you’re somehow associated with this,” recalls Williams.

In 2017, Williams hit the FBI’s mandatory retirement age of 57. He soon found a perfect outlet for his 9/11 obsession: He’s working with attorneys representing the families and survivors of the 9/11 attacks in their civil suit against the Kingdom of Saudi Arabia, which is still in the pre-trial phase.

His work is done under a protective order that prevents him from sharing what he’s learned from depositions and from reviewing still-classified documents from Operation Encore, the FBI’s investigation of Saudi government links to 9/11.

However, he’s unequivocal about what it adds up to: “The evidence is there.”

His work on the case goes against the wishes of the FBI. As Williams told me in a 2018 story that broke the news, a lawyer from the FBI’s Office of the General Counsel told him not to join the plaintiffs’ legal team, saying it could impact “other pending litigation” and undermine the pursuit of warm relations with Saudi Arabia.

This time, though, Ken Williams gets to set his own priorities.

This article was originally featured at Stark Realities and is republished with permission.