Surveillance also indicated that the courier was living in the guard-house not the main house and that the "pacer" was living in the main house.

By mid-February, intelligence from multiple sources was clear enough that Mr. Obama wanted to "pursue an aggressive course of action," a senior administration official said. Over the next two and a half months, Mr. Obama led five meetings of the National Security Council focused solely on whether bin Laden was in that compound and, if so, how to get him, the official said.

President Obama considered attacking with B-2 stealth bombers flying non-stop from the U.S., but instead he chose the option that offered the best chance of coming away with proof bin Laden had been killed -- a helicopter raid by Navy SEALs.

It was also the riskiest option -- American commandos operating without permission deep inside Pakistani territory. The operation was such a tightly held secret that when the SEALs began training on a mockup of the compound, they were not told whom the real target was.

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