Khalid Muhammad Abdallah al-Mihdhar (Arabic: خالد المحضار, romanized: Khālid al-Miḥḍār; also transliterated as AL Mihdhar; 16 May 1975[a] – 11 September 2001) was a Saudi terrorist hijacker.

Upon arriving in San Diego County, California, al-Mihdhar and al-Hazmi were to train as pilots, but spoke English poorly and did not do well with flight lessons.

[2] Little is known about his life before the age of 20, when he and childhood friend Nawaf al-Hazmi went to Bosnia and Herzegovina to fight with the mujahideen in the Bosnian War.

Al-Mihdhar and al-Hazmi were among the first group of participants selected for the operation, along with Tawfiq bin Attash and Abu Bara al Yemeni, al-Qaeda members from Yemen.

Based on information uncovered by the FBI in the 1998 United States embassy bombings case, the National Security Agency (NSA) began tracking the communications of Hada, al-Mihdhar's father-in-law.

In Malaysia, the group stayed with Yazid Sufaat, a local Jemaah Islamiyah member, who provided accommodation at Hambali's request.

The Malaysians reported that al-Mihdhar spoke at length with bin Attash, and he met with Fahd al-Quso and others who were later involved in the USS Cole bombing.

[21] On 15 January 2000, al-Mihdhar and al-Hazmi arrived at Los Angeles International Airport from Bangkok and were admitted as tourists for a period of six months.

[22] On 1 February 2000—17 days upon entering the United States—the two men encountered Omar al-Bayoumi and Caysan Bin Don at a halal food restaurant on Venice Boulevard in Culver City.

[25] While in San Diego, witnesses told the FBI he and al-Hazmi had a close relationship with Anwar Al Awlaki, an imam who served as their spiritual advisor.

[27] Neighbors thought that al-Mihdhar and al-Hazmi were odd because months passed without the men getting any furniture, and they slept on mattresses on the floor, yet they carried briefcases, were frequently on their mobile phones, and were occasionally picked up by a limousine.

Al-Mihdhar and Al-Hazmi raised some suspicion when they offered extra money to their flight instructor, Rick Garza, if he would train them to fly jets.

[39] On 10 June, he returned to Saudi Arabia for a month, where he applied to re-enter the United States through the Visa Express program, indicating that he intended to stay at a Marriott hotel in New York City.

[40] On 4 July, al-Mihdhar returned to the United States, arriving at New York City's John F. Kennedy International Airport,[38] using a new passport obtained the previous month.

[43] On 1 August, al-Mihdhar and fellow Flight 77 hijacker Hani Hanjour drove to Virginia in order to obtain driver's licenses.

[46] On 22 August, al-Mihdhar and al-Hazmi tried to purchase flight tickets from the American Airlines online ticket-merchant, but had technical difficulties and gave up.

The FBI headquarters received a copy of the Visa Express application from the Jeddah embassy on August 24, showing the New York Marriott as al-Mihdhar's destination.

An agent in the New York office sent an e-mail to FBI headquarters saying, "Whatever has happened to this, someday someone will die, and the public will not understand why we were not more effective and throwing every resource we had at certain 'problems.'"

[16][56] On 10 September 2001, al-Mihdhar and the other hijackers checked into the Marriott Residence Inn in Herndon, Virginia, near Washington Dulles International Airport.

[57] Saleh Ibn Abdul Rahman Hussayen, a prominent Saudi Arabian government official, was staying at the same hotel that night, although there is no evidence that they met or knew of each other's presence.

[59] At 7:15 a.m., al-Mihdhar and Moqed checked in at the American Airlines ticket counter[60] and arrived at the passenger security checkpoint at 7:20 a.m.[61] Both men set off the metal detector and were put through secondary screening.

[64] By 7:50 a.m., al-Mihdhar and the other hijackers, carrying knives and box cutters, had made it through the airport security checkpoint and boarded Flight 77 to Los Angeles.

Quso was able to identify al-Mihdhar, al-Hazmi and bin Attash in photos provided by the FBI, and he also knew Marwan al-Shehhi, a hijacker aboard United Airlines Flight 175.

[73] On 12 September 2001, the Toyota Corolla purchased by al-Mihdhar was found in Dulles International Airport's hourly parking lot.

Inside the vehicle, authorities found a letter written by Mohamed Atta, a hijacker aboard American Airlines Flight 11; maps of Washington, D.C. and New York City; a cashier's check made out to a Phoenix, Arizona, flight school; four drawings of a Boeing 757 cockpit; a box cutter; and a page with notes and phone numbers, which contained evidence that led investigators to San Diego.

[76] The German magazine Der Spiegel later investigated the BBC's claims of "living" hijackers and reported they were cases of mistaken identities.

Phillpott said that Shaffer was "relying on my recollection 100 percent", and the Defense Department Inspector General's report indicated that Philpott strongly supported the social network analysis techniques used in Able Danger, and might have exaggerated claims of identifying the hijackers.