Twenty-five years later, the FBI’s handling of possible Saudi links to 9/11 looks increasingly difficult to explain

ProPublica has reconstructed what happened to evidence seized from Omar al-Bayoumi, the Saudi man who provided extraordinarily useful assistance to the first two 9/11 hijackers who arrived in California.

Bayoumi helped Nawaf al-Hazmi and Khalid al-Mihdhar find an apartment, co-signed their lease, helped establish a bank account, temporarily provided their deposit and introduced them to a network of people in San Diego. He always maintained that he encountered them by chance after visiting the Saudi consulate in Los Angeles.

What investigators were given

After 9/11, British police arrested him at the FBI’s request and seized computers, documents and more than 80 videotapes. A British terrorism investigator now tells ProPublica that US agents gave his team surprisingly little background information during interrogation. More strangely, the FBI’s San Diego investigators were later asked to review only five of the dozens of tapes. One seized video showed Bayoumi extensively filming the US Capitol; Saudi lawyers say it was simply tourist footage.

Evidence that emerged later

Evidence accumulated later. Operation Encore, the FBI team that revisited Saudi connections, found witnesses saying Saudi cleric Fahad al-Thumairy helped arrange the hijackers' movements before their supposedly accidental meeting with Bayoumi. Phone records connected Bayoumi around that period to Thumairy, other Saudi religious officials and Anwar al-Aulaqi. Most strikingly, FBI memoranda written in 2017 concluded that Bayoumi had been receiving money as a co-optee — essentially a part-time asset — of Saudi intelligence from the late 1990s through September 11. The investigators who had spent years examining him did not see those memos until they were declassified years later.

What remains unproven

This still does not establish that Saudi Arabia knowingly participated in the 9/11 plot, or even that Bayoumi knew what the hijackers were planning. Saudi Arabia denies involvement. The troubling part is narrower: FBI leadership repeatedly presented the “unwitting helper” interpretation with considerably more confidence than the evidentiary record now seems to justify, while investigators pushing the Saudi angle say headquarters repeatedly resisted them. Operation Encore was finally dismantled in 2016 — just before the FBI memos confirming Bayoumi’s intelligence relationship.

This is less a newly solved 9/11 mystery than an investigation into why American institutions prematurely closed off one of the attack’s most important unresolved questions.