Pakistan has repeatedly come under fire for the ISI's apparent policy of harboring terrorists in the hope of using them later as a foreign policy instrument. Pakistan has repeatedly claimed that it never was aware of Bin Laden's location within the country.
But one official told Gall that the U.S. had direct evidence that ISI chief Lt. Gen. Ahmed Shuja Pasha "knew of Osama's whereabouts."
Gall adds that Pakistan allowed Bin Laden allowed to travel and have extensive correspondence with other militant leaders in Pakistan's volatile North West Frontier Province and elsewhere.
The al-Qaeda leader's convoys reportedly traveled "in plain sight" and were waved through any security checkpoints.
According to a Pakistani government inquiry, Bin Laden was once even stopped for a speeding ticket before being allowed to continue on his way.
Although Gall's report is not conclusive evidence of Pakistan's deliberate harboring of Bin Laden, the ISI has long been accused of supporting and training the Taliban. From the 1990s to 2001 the ISI openly funded and supported the Taliban during Afghanistan's civil war.
And Bin Laden's Abbottabad compound was located just a few hundred meters away from one of Pakistan's top military academies.
Gall, who investigated the story for more than two years, reports that actually had a special desk set up dedicated to handling Bin Laden.
According to one inside source, the ISI actually ran a special desk assigned to handle Bin Laden. It was operated independently, led by an officer who made his own decisions and did not report to a superior. He handled only one person: Bin Laden ... 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.
Although the ISI claimed to have shut links to the Taliban after September 11, analysts believed their relationship was too cherished to discard. A NATO report from 2012 alleged that the ISI continued to help coordinate Taliban and al Qaeda strategy in Afghanistan.
Pakistan had much to gain from harboring Bin Laden. By maintaining relations with the Taliban and al Qaeda, Pakistan could leverage the groups' militant activity in order to continue receiving funding from the United States while also having continued influence in Afghanistan.
Of course, Pakistan continues to deny these claims and the White House claimed there was "no smoking gun" linking Bin Laden and the Pakistani government or intelligence services.