In this May 3, 2011, file photo, local residents gather outside a house, where al-Qaeda leader Osama bin Laden was caught and killed in Abbottabad, Pakistan. (AP Photo/B.K.Bangash,File)

Ever since the discovery and death of Osama bin Laden in a leafy town not far from Islamabad in May 2011, it's been an open secret that some element within the Pakistani state must have played a role in giving the world's most wanted terrorist safe haven.

But for years, Pakistan's government and its military have publicly denied any connection with harboring bin Laden. The U.S. raid on the al-Qaeda leader's compound was treated as a surprise and a humiliation. A 2013 report by the Abbottabad Commission, an official government inquiry into the events surrounding bin Laden's capture, charged Pakistan's civilian and military establishment with "gross incompetence" that led to "collective failures." But it said little directly about collusion.

That narrative is starting to change. In an interview with Al Jazeera scheduled to air in April, a retired Pakistani spy chief admitted that it was "probable" Pakistan's notorious military intelligence agency, known as the ISI, knew of bin Laden's location. Lt. Gen. Asad Durrani, who headed the ISI in the early 1990s, was speaking to Al Jazeera's Mehdi Hassan, host of its "Head to Head" program.

Here's part of Durrani's response to a question posed by Hassan, asking the former ISI chief how it was possible that the agency could have had no knowledge of bin Laden's whereabouts.

My assessment […] was it is quite possible that they [the ISI] did not know but it was more probable that they did. And the idea was that at the right time, his location would be revealed. And the right time would have been, when you can get the necessary quid pro quo -- if you have someone like Osama bin Laden, you are not going to simply hand him over to the United States.

The implication here is that bin Laden would have been a bargaining chip in the complicated shadow war playing out in the region, as the United States struggled to tamp down a Taliban insurgency in neighboring Afghanistan. The ISI, of course, has played a double game for some time -- and is believed to have both helped engineer the creation of the Taliban as well as support other Islamist militant groups that target arch-rival India.

In an expose published last year in the New York Times, veteran reporter Carlotta Gall claimed that the ISI -- formally known as the Directorate for Inter-Services Intelligence -- even had a special desk dedicated to handling bin Laden.

"It was operated independently, led by an officer who made his own decisions and did not report to a superior," reported Gall. "The desk was wholly deniable by virtually everyone at the ISI — such is how supersecret intelligence units operate — but the top military bosses knew about it, I was told."

That's a claim that's still difficult to corroborate. But Durrani's admission offers a glimpse into the opaque workings of institutions like the ISI and the Pakistani military, which has played a domineering role in Pakistani politics for much of the country's history.

"The admission of incompetence was probably done on political reasons," Durrani tells Al Jazeera, referring to the findings of the 2013 Abbottabad Commission. "As far as the people of Pakistan were concerned, it was going to be very uncomfortable for them that their government, you know, is in cahoots now with the United States and gets hold of Osama bin Laden" -- a man who, Durrani says, was "an admired figure" in Pakistan.

Durrani, a noted commentator, has made the last point before. In a piece published by the Atlantic just a few months after bin Laden's death (and cited also by Politico), the former ISI chief speculated: "If [Pakistan's] leadership was to choose between inability to defend national borders and complicity with the US … it would rather concede incompetence."