From two of the official statements on Bin Laden's demise, in turn this:
From the outset of the administration, the President has placed the highest priority in protecting the nation from the threat of terrorism. In line with this, we have pursued an intensified, targeted, and global effort to degrade and defeat al Qaeda. Included in this effort has been a relentless set of steps that we've taken to locate and bring Osama bin Laden to justice. Indeed, in the earliest days of the administration, the President formally instructed the intelligence community and his counterterrorism advisors to make the pursuit of Osama bin Laden, as the leader of al Qaeda,... a top priority.
And - the man himself - this:
And so shortly after taking office, I directed Leon Panetta, the director of the CIA, to make the killing or capture of bin Laden the top priority of our war against al Qaeda, even as we continued our broader efforts to disrupt, dismantle, and defeat his network.
From which we may infer that the criminal against humanity who formerly went under the name of Osama bin Laden was eventually killed because the war formerly known as the war on terror continued to be a... war on terror. To mark the continuity I also bring you these words from George W. Bush, welcoming the latest news:
This momentous achievement marks a victory for America, for people who seek peace around the world, and for all those who lost loved ones on September 11, 2001. The fight against terror goes on...