Two intelligence sources tell NBC News that the year before the U.S. raid that killed Osama bin Laden, a “walk in” asset from Pakistani intelligence told the CIA where the most wanted man in the world was hiding – and these two sources plus a third say that the Pakistani government knew where bin Laden was hiding all along…

The NBC News sources who confirm that a Pakistani intelligence official became a “walk in” asset include the special operations officer and a CIA officer who had served in Pakistan. These two sources and a third source, a very senior former U.S. intelligence official, also say that elements of the ISI were aware of bin Laden’s presence in Abbottabad. The former official was emphatic about the ISI’s awareness, saying twice, “They knew.”

Another top official acknowledged to NBC News that the U.S. government had long harbored “deep suspicions” that ISI and al Qaeda were “cooperating.” And a book by former acting CIA director Mike Morrell that will be published tomorrow says that U.S. officials could not dismiss the possibility of such cooperation.