Ratchford managed Parkwood Apartments in San Diego, California, when Bayoumi, a Saudi in his early 40s, moved into unit 152 in September 1999 with his family. He quickly became a fixture at her pool parties — "always so bubbly and smiling," she recalls.
A few months later, Bayoumi introduced Ratchford to two men she describes as "unassuming" and "polite." Those men would hijack American Airlines Flight 77 and crash it into the Pentagon on 11 September 2001. In total, 19 al-Qaeda hijackers commandeered four aircraft that day, including the two that struck the World Trade Center towers and a fourth that crashed in Pennsylvania.
"It's almost impossible for me to wrap my head around who he said he was, and who he really is. I still struggle with that," Ratchford told the BBC in her first public account.
Bayoumi's role has long been scrutinised by the 9/11 Commission, which noted he provided extensive assistance to the hijackers. He returned to Saudi Arabia days before the attacks and was never charged. The $1 trillion (£733bn) civil lawsuit now alleges Saudi officials directly supported Bayoumi, whom the plaintiffs describe as a Saudi intelligence asset.
Ratchford said she felt taken in: "Whenever I had parties he would come and be a part of the activities … I enjoyed going over." The experience has haunted her for 25 years.