He had previously been identified by the CIA as an associate of Khalid al-Mihdhar, a fellow hijacker on that flight. The INS was advised in August 2001 to put him and al-Mihdhar on a watch list to prevent entry into the U.S., but passport records revealed that they had both previously entered at Los Angeles National Airport in 2000, then in the New York area in 2001. The FBI was subsequently contacted, and began to search for them on August 21, but could not determine their whereabouts.
After the attack, it was learned that they rented rooms in suburban San Diego from Abdussattar Shaikh, a retired professor, beginning in September 2000. Al-Hazmi stayed there until December.