When the PGA Tour announced a long-term partnership with LIV Golf, the upstart organization bankrolled by Saudi Arabia’s sovereign wealth fund, no one sounded angrier than survivors of the 9/11 attacks and the families of those who were killed.

The pact on June 6 marked an abrupt reversal for the PGA, which had fought LIV Golf since it emerged in 2021. The rival league courted star golfers with vast payouts that were widely seen as part of a global public-relations campaign by the Saudi government.

“All of these PGA players and PGA executives who were talking tough about Saudi Arabia have done a complete 180,” one spokesperson for the families, Brett Eagleson, said in an interview. “All of a sudden they’re business partners? It’s unconscionable.”

Before the new alliance, PGA officials had highlighted the Saudi government’s alleged role in the 9/11 attacks, along with the kingdom’s record of human rights abuses, as important reasons for their opposition to LIV Golf.

The Saudi government has long denied that it provided any support for the attacks. But, over the past few years, evidence has emerged that Saudi officials may have had more significant dealings with some of the plotters than U.S. investigations had previously shown.

Since 2017, the 9/11 families and some insurance companies have been suing the Saudi government in a Manhattan federal court, claiming that Saudi officials helped some of those involved in the Qaida plot.

The Saudi royal family was a declared enemy of al-Qaida. In the early 1990s, it expelled Osama bin Laden, the son of a construction magnate, and stripped him of his citizenship. At the same time, the kingdom funded an ambitious effort to propagate its radical Wahhabi brand of Islam around the world and tolerated a religious bureaucracy that was layered with clerics sympathetic to al-Qaida and other militant Islamists.

From the start of the FBI’s investigation into a possible support network for the 9/11 plot, one of its primary suspects was a supposed Saudi graduate student who helped settle the first two hijackers to arrive in the United States after they flew into Los Angeles in January 2000.

The middle-aged student, Omar al-Bayoumi, told U.S. investigators that he met the operatives by chance at a halal cafe near the Saudi Consulate in Culver City, California. The two men, Nawaf al-Hazmi and Khalid al-Mihdhar, were trained as terrorists but spoke virtually no English and were poorly prepared to operate on their own in Southern California.

Bayoumi insisted he was just being hospitable when he found Hazmi and Mihdhar an apartment in San Diego, set them up with a bank account and introduced them to a coterie of Muslim men who helped them for months with other tasks — from buying a car and taking English classes to their repeated but unsuccessful attempts to learn to fly.

As ProPublica and The New York Times Magazine detailed in an in-depth report on the FBI’s secret investigation of the Saudi connection in 2020, agents on the case suspected that Bayoumi might be a spy. He seemed to spend most of his time hanging around San Diego mosques, donating money to various causes and obtrusively filming worshippers with a video camera.

Yet both the FBI and the bipartisan 9/11 Commission accepted Bayoumi’s account almost at face value. In a carefully worded joint report in 2005, the CIA and FBI asserted that they had found no information to indicate that Bayoumi was a knowing accomplice of the hijackers or that he was a Saudi government “intelligence officer.”

But FBI documents that were just made public last year sharply revised that assessment.

While living in San Diego, one FBI document concludes, Bayoumi was paid a regular stipend as a “cooptee,” or part-time agent, of the General Intelligence Presidency, the Saudi intelligence service. The report adds that his information was forwarded to the powerful Saudi ambassador in Washington, D.C., Prince Bandar bin Sultan, a close friend to both presidents Bush and their family. The Saudi Embassy in Washington did not immediately respond to questions about Bandar’s alleged relationship with Bayoumi.

As Bayoumi was helping the hijackers, FBI documents show, he was also in close contact with members of a Saudi religious network that operated across the United States. He also dealt extensively with Anwar al-Awlaki, a Yemeni American cleric who the documents suggest was more closely involved with the hijackers than was previously known. Awlaki later became a leader of al-Qaida in the Arabian Peninsula and was killed in a 2011 drone strike ordered by President Barack Obama.

One of the Saudi officials with whom Bayoumi appeared to work, Musaed al-Jarrah, was both a key figure in the Saudi religious apparatus in Washington and a senior intelligence officer. After being expelled from the United States, Jarrah returned to Riyadh and worked for years as an aide to Prince Bandar on the Saudi national security council.

Another Saudi cleric with whom Bayoumi worked, Fahad al-Thumairy, was posted to Los Angeles as both a diplomat at the Saudi Consulate and a senior imam at the nearby King Fahad Mosque — a pillar of the global effort to spread Wahhabi Islam that had opened in mid-1998.

According to another newly declassified FBI document from 2017, an unnamed source told investigators that Thumairy received a phone call shortly before the two hijackers arrived in Los Angeles from “an individual in Malaysia” who wanted to alert him to the imminent arrival of “two brothers … who needed their assistance.”

In mid-December 1999, according to the 9/11 Commission report, a key Saudi operative in the plot, Walid bin Attash, flew to Malaysia to meet with Hazmi and Mihdhar. Although the men were kept under surveillance by Malaysian security agents, they were allowed to fly on to Bangkok and then Los Angeles, using Saudi passports with their real names. The FBI source said that Thumairy arranged for Mihdhar and Hazmi to be picked up at the Los Angeles International Airport and brought to the King Fahad Mosque, where they met with him. Thumairy and Jarrah have both denied helping the hijackers.

The FBI revelations were especially stinging for the 9/11 families because previous administrations made extraordinary efforts to keep them under wraps. President Donald Trump, who promised to help the families gain access to FBI and CIA documents, instead fought to shield them as state secrets. (Trump has been a vocal supporter of LIV Golf, hosting several of its tournaments at his golf courses and saying after the merger, “The Saudis have been fantastic for golf.”)

The more recent disclosures — which came in documents declassified under an executive order that President Joe Biden issued just before the 20th anniversary of the attacks — are now at the center of the federal litigation in New York. While the families are pressing to reopen discovery in the case based on the new FBI information about Bayoumi and others, lawyers for the Saudi government continue to insist there is no evidence of the kingdom’s involvement in the plot.

To prove their case, the families must show that people working for the Saudi government either aided people they knew were planning a terrorist action in the United States or helped members of a designated terrorist organization like al-Qaida. At the time that Bayoumi aided Hazmi and Mihdhar in California, officials have said, the CIA and Saudi intelligence had identified the two as Qaida operatives.

The two federal judges overseeing the Manhattan litigation have yet to rule on requests from the families, based on the newly declassified FBI documents, for further inquiries to the Saudi intelligence service.

The PGA official who brokered the new alliance with LIV Golf, James J. Dunne III, told the Golf Channel he was confident that the Saudi officials with whom he negotiated were not involved in the 9/11 plot. Dunne, an investment banker, added, “And if someone can find someone that unequivocally was involved with it, I’ll kill him myself.”

Eagleson, whose father, John Bruce Eagleson, died in the same south tower of the World Trade Center where 66 employees of Dunne’s bank were killed, suggested that he read the declassified FBI documents about Bayoumi, Thumairy and other Saudis. “It’s the same government,” Eagleson said.