WASHINGTON – An al-Qaida suspect who was subjected to harsh interrogation techniques at a secret CIA prison in early 2004 provided his interrogators with a clue — the nom de guerre of a mysterious courier — that ultimately proved crucial to finding and killing Osama bin Laden, officials said Wednesday.

The CIA had approved use of sleep deprivation, slapping, nudity, water dousing and other coercive techniques at the now-closed CIA “black site” in Poland where the Pakistani-born detainee, Hassan Ghul, was held, according to a 2005 Justice Department memo, which cited Ghul by name. Two U.S. officials said Wednesday that some of those now-prohibited practices were directed at Ghul.

Ghul was not water boarded, or subject to near-drowning, the most notorious interrogation technique and one that critics describe as torture.

Two other CIA prisoners — al-Qaida’s operations chief Khalid Sheikh Mohammed, and his successor, Abu Faraj al-Libbi — gave their interrogators false information about the courier after they were water boarded repeatedly, U.S. officials said.

Those lies also played a role in the decade-long manhunt, however. Over time, they were viewed as evidence by CIA analysts that bin Laden’s top deputies were trying to shield a figure who might be a link to the al-Qaida leader’s hide-out, according to U.S. officials briefed on the analysis. “The fact that they were covering it up suggested he was important,” a U.S. official said.

In the end, intelligence gained from interviews with numerous detainees, high-tech eavesdropping and surveillance, and other investigative spadework provided insights into people who were close to bin Laden. No one source or bit of intelligence was so decisive or critical that it instantly solved the puzzle or ended the painstaking hunt for the world’s most wanted terrorist, officials said.

The nuances of that complex chain of events were often lost Wednesday amid a renewed public debate about the efficacy and morality of coercive interrogations that the CIA carried out under President George W. Bush.

“I think the issue has been mischaracterized on both sides,” said a former CIA official who was involved in internal debate over the so-called “enhanced interrogation techniques” program at the time. “The people who say ‘enhanced interrogation techniques’ directly led to catching bin Laden are wrong, and the people who say they had nothing to do with it are also wrong.”

The current CIA director, Leon Panetta, said it was impossible to know if the same information could have been gleaned without using those techniques, which have been banned under President Obama.

“The debate about whether we would have gotten the same information through other approaches, I think, is always going to be an open question,” Panetta told NBC News on Tuesday.

Panetta did not say — and other administration officials adamantly denied — that coercive interrogation techniques directly led to finding bin Laden.

“There is no way that information obtained by (enhanced interrogation techniques) was the decisive intelligence that led us directly to bin Laden,” said Tommy Vietor, spokesman for the National Security Council at the White House.

“It took years of collection and analysis from many different sources to develop the case that enabled us to identify this compound, and reach a judgment that bin Laden was likely to be living there,” Vietor said. “The bottom line is this: If we had some kind of smoking-gun intelligence from water boarding in 2003, we would have taken out Osama bin Laden in 2003.”

The Bush administration abandoned water boarding by in 2004, and closed the CIA’s secret web of prisons. All the detainees were transferred to Guantanamo Bay by 2007.

The Obama administration has forsworn those interrogation tactics, and the CIA no longer captures or interrogates terror suspects, the agency says. The CIA has sharply increased the use of armed Predator drones and military commando raids to kill them, or passed intelligence tips to other governments to capture or kill them instead.

Things were much different in January 2004, when Kurdish military forces in northern Iraq picked up Ghul, an al-Qaida courier who was carrying a letter sent by the Iraqi terrorist leader Abu Musab al-Zarqawi to bin Laden.

Ghul quickly disappeared into the CIA’s network of secret prisons, and became one of 28 detainees subject to “enhanced interrogation techniques,” according to the Justice Department memo, which was publicly released in 2009.