A private letter from CIA chief Leon Panetta to Senator John McCain (R-AZ) confirms that the so-called enhanced interrogation techniques put in place by the Bush administration did not reveal intelligence about Abu Ahmed al-Kuwaiti, the courier that eventually led the U.S. to Osama bin Laden.

The letter was obtained by The Washington Post and a CIA spokesperson confirmed its authenticity.

"Let me further point out that we first learned about the facilitator/courier’s nom de guerre from a detainee not in CIA custody in 2002," the letter stated. "It is also important to note that some detainees who were subjected to enhanced interrogation techniques attempted to provide false or misleading information about the facilitator/courier. These attempts to falsify the facilitator/courier’s role were alerting."

"In the end, no detainee in CIA custody revealed the facilitator/courier’s full true name or specific whereabouts," Panetta added. "This information was discovered through other intelligence means."

Former Bush officials and some Republicans have insisted that enhanced interrogation techniques like waterboarding resulted in information that eventually led to bin Laden's whereabouts.

Last week, Sen. McCain wrote an op-ed piece in the The Washington Post claiming that bin Laden's death should not be used to justify torture. In his article, he cited information he received from Panetta, but he did not release that information to the public.