On the sixth anniversary of the daring SEAL Team 6 raid that killed Usama bin Laden in Pakistan, Dr. James Mitchell revealed how the CIA's enhanced interrogations helped locate the elusive al Qaeda leader.

Mitchell, the author of "Enhanced Interrogation," said on "Fox & Friends" that key information was provided by Ammar al-Baluchi, the nephew of 9/11 mastermind Khalid Sheikh Muhammad.

He said it was through interrogations of al-Baluchi that the United States learned about the courier delivering letters to bin Laden.

Mitchell recalled that Guantanamo Bay detainees developed a way to communicate with each other through messages they believed were secret.

"[KSM] put out a message in what he thought was a clandestine way of communicating with other detainees to not talk about the courier. ... That signaled to the interrogators that that man was important and we needed to do more," said Mitchell, who spent thousands of hours interviewing Muhammad.

Mitchell was asked by the CIA to help with interrogations following the 9/11 attacks after previously training U.S. service members on how to resist interrogation by the enemy. 

He said finding bin Laden was the work of teams of analysts taking small pieces of data and plugging them into the "giant matrix" to connect the dots. 

The U.S. intelligence community's hunt for bin Laden, including the al-Baluchi interrogation, were depicted in the film "Zero Dark Thirty."

Watch the compelling interview above and take a look back at former Navy SEAL Robert O’Neill's account of the moment he killed bin Laden.

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Earlier in the show, Geraldo Rivera looked back at the night in 2011 that the world learned of bin Laden's death.