WASHINGTON — The killing of Osama bin Laden in May 2011 was hailed by current and former CIA officials as the crowning justification for the use of harsh interrogation tactics. High-value detainees, when subjected to those methods, provided intelligence that the officials said helped lead the spy agency to a mysterious courier and, ultimately, to the terrorist leader himself.

The Senate Intelligence Committee report released Tuesday upends that version of history, providing an alternate case study that revives questions about the agency’s account. The report asserts that the role of harsh interrogation techniques was greatly exaggerated.

“A review of CIA records found that the initial intelligence obtained, as well as the information the CIA identified as the most critical – or the most valuable – on Abu Ahmad al-Kuwaiti, was not related to the use of the CIA’s enhanced interrogation techniques,” investigators concluded.

The role the CIA detention and interrogation program played in the hunt for bin Laden is one of the most pivotal questions in assessing the effectiveness of the agency’s response to the Sept. 11 attacks. The Senate report notes that even in the weeks before the raid in Abbottabad, Pakistan, the CIA’s Office of Public Affairs had prepared “agreed-upon language” to be released that would stress “the critical nature of the detainee reporting in identifying bin Laden’s courier.”

Almost from the start of the search for bin Laden, the CIA was focused on the al-Qaida leader’s inner circle. The Senate report found that the agency made quick progress, obtaining a phone number associated with al-Kuwaiti as soon as Jan. 1, 2002, allowing the CIA to begin storing his calls. The following year, the CIA had obtained an email address believed to be associated with al-Kuwaiti.

A stream of information about the courier began trickling into the agency. The CIA learned in 2002 from detainees held by other countries that the courier was close to bin Laden and Khalid Sheik Mohammed, the self-admitted mastermind of the Sept. 11 attacks.

That year, the CIA received information on the courier’s family that the agency would later cite as pivotal in identifying al-Kuwaiti, according to the Senate report.

The agency “received significant corroborative reporting on al-Kuwaiti’s age, physical appearance, and family from detainees held in the custody of foreign governments and the U.S. military,” the report says.

Despite the seemingly valuable intelligence, the CIA did not yet understand that al-Kuwaiti was a key player who could lead them to bin Laden.

In March 2003, working with Pakistan, the CIA captured Mohammed and found an email associated with the courier on Mohammed’s laptop. Within days, Mohammed was taken to the CIA’s secret prison in Poland and interrogated.

Mohammed was waterboarded 183 times and exposed to other harsh interrogation techniques. When asked about a bin Laden courier named “Abu Ahmed,” Mohammed dissembled, providing his interrogators with a false name. Mohammed repeatedly played down the courier’s significance in al-Qaida.

Still, Mohammed did confirm to interrogators that the courier had worked with a suspected terrorist named Hassan Ghul. It was Ghul, detained in early 2004, who told the CIA about the importance of the courier – but he did so before he was subjected to harsh questioning, the Senate report says.

“He sang like a tweetie bird,” a CIA officer told the agency’s inspector general. “He opened up right away and was cooperative from the outset.”

According to the report, Ghul said that bin Laden’s “security apparatus would be minimal, and that the group likely lived in a house with a family somewhere in Pakistan.”

Ghul speculated that “Abu Ahmed likely handled” all of bin Laden’s needs, “including moving messages” to Abu Faraj al-Libi, another top bin Laden lieutenant.

Soon Ghul was moved to the CIA prison in Romania to face harsh questioning. During and after “the use of the CIA’s enhanced interrogation techniques, Ghul provided no other information of substance on al-Kuwaiti,” the Senate report found. Nor, the Senate said, did al-Libi.

When the CIA went back to Mohammed in 2005 to press him on al-Kuwaiti, Mohammed insisted al-Kuwaiti was not a courier.

It would take another seven years before the CIA was confident enough about al-Kuwaiti’s ties to bin Laden to launch the raid in Abbottabad. That raid also killed al-Kuwaiti.

On May 4, 2011, two days after bin Laden was killed, a CIA officer told the Senate Intelligence Committee that it was two detainees who helped them understand the courier’s position in al-Qaida: Abu Zubaida, a suspected terrorist with links to al-Qaida, who the agency said discussed al-Kuwaiti in 2005, and a detainee known as Riyadh the Facilitator who was held by another government but never put through harsh interrogation.

The Senate report disputes that claim and says CIA records show Abu Zubaida did not mention al-Kuwaiti when he was first captured and the following year denied he knew him.

“There are no CIA records of Abu Zubaydah discussing Abu Ahmad al-Kuwaiti in 2002,” the Senate report says, adding that although Abu Zubaida eventually mentioned al-Kuwaiti in 2005, officers described the information as “speculative.”

In a detailed response to the committee report, the CIA rejected the study’s interpretation of events leading to the killing of bin Laden. It reiterates that coercive measures helped, saying the tactics led two detainees in agency custody, Ammar al-Baluchi and Ghul, to provide important clues to the courier.

It was “impossible to know in hindsight” whether interrogators could have obtained the same information that helped locate bin Laden without using enhanced techniques, the agency said.

“However, the information we did obtain from these detainees played a role – in combination with other important streams of intelligence – in finding the al-Qaida leader.”