(CNN) -- The operation that led to the killing of al Qaeda leader Osama bin Laden took shape after detainees identified a trusted bin Laden courier as someone who may have been living with and protecting the militant leader, senior administration officials said.
That courier became a key lead in locating bin Laden, the officials said.
The officials provided details on the origins of the operation and the raid that led to bin Laden's killing:
• Four years ago: Officials uncovered the courier's identity.
• Two years ago: Investigators identified areas of Pakistan where the courier and his brother lived.
What was Pakistan's part?
Inside the place bin Laden was killed
Hideout wasn't remote cave after all
The life of Osama bin Laden
• August: The residence of the courier and his brother was found in Abbottabad, 30 to 35 miles north of Islamabad, Pakistan's capital.
• September: The CIA worked with President Barack Obama "on a set of assessments that led it to believe that in fact it was possible" bin Laden may be at the compound in Abbottabad.
• February: U.S. officials concluded there was a "sound intelligence basis" for pursuing bin Laden at that location.
• March and April. Obama held a series of National Security Council meetings "to develop courses of action to bring justice to Osama bin Laden." There were at least five meetings: March 14, March 29, April 12, April 19 and Thursday.
• Friday. Obama gave the final order to pursue the operation.
How U.S. forces killed Osama bin Laden
• Sunday. After months of decision-making and planning, a U.S. military team conducted a small helicopter raid on the compound. The officials did not provide a breakdown of team members, but a senior U.S. defense official said U.S. Navy SEALs were involved in the operation.
The senior administration officials provided these details of the raid:
• The team was in the compound for 40 minutes. It did not encounter any local authorities during the raid.
• Bin Laden resisted the assault force and died in a firefight. Along with bin Laden, three adult males were killed.
• Two were believed to be the couriers, and one was a son of bin Laden's.
Trail leading to bin Laden began with his trusted courier
• A woman used as a human shield by a male combatant died, and two women were injured.
• A helicopter was lost because of mechanical failure.
• Intelligence on bin Laden was not shared with Pakistan and other countries.
• After the raid, U.S. officials briefed Pakistani and other world leaders.
• Bin Laden has been buried at sea and his body was handled in the Islamic tradition. The officials but did not elaborate.
