"We've grown much better at fusing all sorts of data and have a great deal of capacity to burrow in, once we have a trail," agreed Juan Zarate, who served as deputy national security advisor for combating terrorism under President George W. Bush.
Some of the reforms since the Sept. 11, 2001, attacks clearly paid off. One goal was to dismantle the "stovepipes" that prevented America's 16 intelligence agencies from sharing information that might have detected the attack.
As a result, the National Security Agency, which conducts eavesdropping operations, and the National Geospatial-Intelligence Agency, which handles spy satellite imagery, set up what they called "geocells." Their analysts worked together to integrate communications intercepts, images and other intelligence.
The analysts "drove each other to actually make sense of the half-dots, the shards, the shreds, the nuances that they already had in hand, the hunches," John Inglis, the NSA's deputy director, said in a speech last fall.
The trail that led to Bin Laden's hideout in the city of Abbottabad began with interrogations of detainees in secret CIA prisons. By 2004, officials had the nom de guerre of a courier who they hoped could lead to the Al Qaeda leader, but it was one of many frustrating clues that seemed to go nowhere.
Over time, the Bush administration publicly downplayed Bin Laden's importance. In 2006, the CIA disbanded Alec Station, a special unit that had been set up to track the terrorist leader. CIA operatives, Special Operations teams and Predator drones were transferred from Afghanistan to the Iraq war.
"We diverted seasoned resources," Hoekstra said.
Still, the chase went on. A key break came in 2007, when the CIA learned the courier's real name. U.S. officials do not dispute published reports indicating that NSA intercepts of phone conversations among his family members played a role.
By early 2009, the CIA had begun to focus on the region of northern Pakistan where the courier and his brother lived, although analysts still didn't know the exact location. The two men rarely used cellphones that could be traced, and they took other security precautions to avoid detection, officials said.
In June 2009, President Obama stepped up the hunt. In a memo to CIA chief Leon E. Panetta, he wrote: "In order to ensure that we have expended every effort, I direct you to provide me within 30 days a detailed operation plan for locating and bringing to justice Osama bin Laden."
In August 2010, the CIA finally identified the suspected hideout in Abbottabad, less than a mile from Pakistan's most respected military academy. Spy satellites were used to provide 24-hour surveillance.
On the ground, the CIA recruited a network of spies in Pakistan and set up a safe house where they and their American handlers could secretly monitor the compound with high-tech listening devices and other sensors, according to a Washington Post report that U.S. officials have not disputed.
Panetta briefed eight congressional leaders from both parties in the fall of 2010 and secured millions of dollars in special funding. He acknowledged that the CIA wasn't certain it had found Bin Laden; some senior officials put the odds as low as 40%, other as high as 80%. But Abbottabad still appeared to be the best lead in years.
Obama ultimately gave the go-ahead to send in the Navy SEALs. But Panetta was in charge when the team crossed into Pakistani airspace about 1 a.m. Monday. The CIA had command because the covert operation was undertaken without permission from Pakistan, officials said.
As silent video streamed in, presumably from a stealthy drone hovering high over the compound, Panetta narrated the action from the 7th-floor conference room at CIA headquarters for Obama and his war council in the White House situation room.
It was a long way from 2001, when CIA officers in Afghanistan pleaded for weeks before the Pentagon finally approved sending Special Operations teams, according to a CIA officer who was there.
"This mission goes to the heart of what the CIA is all about," Panetta said Saturday in a statement. "Since 9/11, this is what the American people have expected of us. In this critical operation, we delivered."
Photos: The death of Osama bin Laden