(CNN) -- A diplomatic source told CNN that the courier who was in close contact with Osama bin Laden and who eventually led the United States to him was a Kuwaiti named Abu Ahmad.
U.S. officials have said that when the identity of the courier -- who they have not named -- was established in 2007 the U.S. began a path to the house in Abbottabad, Pakistan, where the al Qaeda leader was living.
Analysis of assessments of detainees held at the U.S. Navy's detention facility at Guantanamo Bay, Cuba, include several mentions of a man by the name of Abu Ahmad al Kuwaiti, who was reportedly close to Khalid Sheikh Mohammed -- also a Kuwaiti.
The information on the detainee assessments came from U.S. Defense Department documents published by WikiLeaks.
Since the operation that killed bin Laden, U.S. officials have described the courier they were tracking as a protege of Mohammed and another senior member of al Qaeda, Abu Faraj al Libi, a Libyan detainee who was named as al Qaeda's third most senior leader when he was captured in May 2005.
One assessment -- compiled in October 2008 -- concerns a Saudi citizen called Maad al Qathani, the man who was intended to be the "20th hijacker" on 9/11 but who failed to gain entry to the United States.
It said: "Detainee is associated with other key al-Qaida members including senior operations planners Khalid Shaykh Muhammad."
The document later said that al Qathani "received computer training from al-Qaida member Abu Ahmad al-Kuwaiti in preparation for his mission to the U.S."
Al Kuwaiti was then "a senior al Qaeda facilitator and subordinate" of Mohammed. The assessment added: "Al-Kuwaiti worked in the al-Qaida media house operated by KU-10024 (Mohammed) in Kandahar and served as a courier."
Al Qathani reportedly spent about three months in basic training with al Qaeda from December 2000 to February 2001 when he was introduced to bin Laden.
Establishing al Qathani's association with Mohammed, the assessment continued: "Detainee stated UBL told him that since he (detainee) loved to serve his religion, he must go to KU-10024, who will ask him to "do things." It was the first of several encounters with the al Qaeda leader, to whom al Qathani swore a personal oath of allegiance.
The document established that al Kuwaiti was close to bin Laden and traveled with him.
"Al-Kuwaiti was seen in Tora Bora and it is possible al-Kuwaiti was one of the individuals detainee reported accompanying UBL in Tora Bora prior to UBL's disappearance," it says.
In an assessment of al Qathani's intelligence value, the document noted that he "had access to the inner circles of al-Qaida through his interactions with senior al-Qaida members including UBL, (Ayman al-) Zawahiri, KU-10024 (Mohammed) and others."
Al-Zawahiri was al Qaeda's No. 2 man under bin Laden.
Another detainee assessment also mentioned al Kuwaiti. It was of an Indonesian member of al Qaeda called Riduan Isomuddin, who had spent nearly two years in the 1980s fighting jihad in Pakistan and Afghanistan.
He also knew Mohammed, according to the assessment, which said that "in November 2001, detainee and his wife left Kandahar for Karachi. They stayed at the Abu Ahmad al Kuwaiti guest house for two weeks."
Al Qaeda operated a network of guest houses (or safe houses) in Afghanistan and Pakistan before and immediately after the 9/11 attacks.
Isomuddin was captured in August 2003 in Thailand by a joint Thai-U.S. operation and is described in the assessment as a "high-value detainee."
CNN has been unable to confirm with U.S. officials the identity of the courier, but several factors point to al Kuwaiti as the courier who inadvertently led the United States to bin Laden's hiding place: al Kuwaiti's reported history with the organization, his access to senior leaders, his description in the Guantanamo assessment as a courier, and the fact that he was never captured.
CNN has been unable to establish whether he was at the compound when U.S. forces staged their raid or whether he was killed in the operation.