Twenty-five years after the September 11 attacks, previously unseen evidence has raised fresh questions about Omar al-Bayoumi, a man once investigated by the FBI over suspected links to two of the hijackers. A BBC investigation has uncovered footage showing Bayoumi with Anwar al-Awlaki, who later became a senior al-Qaeda figure. The evidence also highlights Bayoumi’s extensive contacts with Saudi government officials. Despite the investigation, the FBI never charged him.

The BBC footage shows Bayoumi embracing Awlaki. Another clip shows the two taking part in military-style paintball sessions near San Diego with other participants, including an official from Saudi Arabia’s Ministry of Islamic Affairs. The FBI, which obtained the footage within days of the 2001 attacks, is now part of the evidence released in a $1 trillion lawsuit filed by 9/11 families against Saudi Arabia. The families allege that Bayoumi assisted Nawaf al-Hazmi and Khalid al-Mihdhar, two of the 19 hijackers who later took part in the Pentagon attack. Saudi Arabia has repeatedly denied any role in the attacks.

Bayoumi moved to San Diego from Saudi Arabia in 1994. He said he had travelled to the United States to study English. Court records later showed that he had largely stopped attending his studies and instead became involved in organising religious events.

The newly revealed footage, filmed in 1997 or early 1998, shows Bayoumi and Awlaki taking part in paintball combat. Some participants wore military-style clothing. Others shouted "Allahu Akbar" while charging in the game. FBI agents investigating Bayoumi after the attacks were told that some participants used the paintball sessions as training for jihad, according to the BBC. Awlaki already had links to al-Qaeda operatives before he became widely known for his extremist activities.

Another clip from January 1998 shows Bayoumi embracing Awlaki. Other footage records Bayoumi meeting Saudi officials and religious figures associated with the Ministry of Islamic Affairs. The material has added to questions about the nature of his connections to Saudi officials and extremist figures.

Bayoumi first came under serious FBI suspicion after investigators found his name on an apartment rental agreement signed by al-Hazmi and al-Mihdhar. The two men later became part of the team that carried out the Pentagon attack.

After moving to Birmingham, England, the Metropolitan Police officers arrested Bayoumi on September 21, 2001. British investigators searched his properties and recovered thousands of documents, photographs and at least 80 videotapes. Among the material was a notebook page showing a drawing of a plane along with mathematical calculations related to its height and distance from a target.

Jodi Westbrook Flowers, a member of the 9/11 families' legal team, told the BBC: "It's the mathematical calculation of the crash. When we figured out what it was, we knew that it was the smoking gun that we'd been looking for."

The BBC reported that British investigators sent copies of the diagram to FBI agents in London. However, detectives questioning Bayoumi were not told about it. The material also did not reach some FBI investigators in San Diego or members of the 9/11 Commission. A federal judge later said the document, on its face, "connects Bayoumi with knowledge of the 9/11 Attacks".

The investigation also found that FBI agents in San Diego repeatedly sought evidence seized by British police. Much of that material remained only metres away at the London police station where Bayoumi was being held. The agents received little of the evidence they requested.

Rick Lambert, who led the San Diego investigation, said: "I believe there is the potential that had we received that evidence and analysed it, that we would have been able to put the pieces of the puzzle together much more quickly."

FBI agents also wanted to question Saudi officials who had links to Bayoumi. According to Lambert, they were denied permission to interview them. Former FBI investigator Steve Moore described the situation to the BBC, saying: "We hit a roadblock so hard, I think we all had airbag burns."

Jeffrey Breinholt, who oversaw 9/11 prosecutors at the Department of Justice, said investigators had considered Bayoumi one of the "hot possibilities for charges". He said the plane diagram could have provided important evidence.

"We've convicted people for less," Breinholt told the BBC.

He also described the paintball footage as "very telling". He said Awlaki’s presence was "pretty damn significant". Despite the evidence and the FBI investigation, Bayoumi was never charged. He has denied any involvement in the attacks, which killed 2,976 people, according to the FBI. Saudi Arabia has also rejected allegations that it or its officials helped the attackers, calling them categorically false. The FBI declined to comment to the BBC.