This undated file picture shows Osama bin Ladin speaking at...

This undated file picture shows Osama bin Ladin speaking at an undisclosed place inside Afghanistan. Credit: Getty Images

It was a compound with 12-to-18-foot walls topped by barbed wire, eight times larger than any surrounding properties in Abbottabad, Pakistan, and constructed five years ago by two trusted al-Qaida couriers.

Those were some of the tip-offs that led to a near-perfect raid by a small team of operatives who crossed into Pakistan on two helicopters and killed Osama bin Laden, senior officials said Sunday night in a background briefing from the White House.

U.S. officials had been intrigued by the two couriers -- brothers -- since the early days after Sept. 11, 2001, when they were identified by al-Qaida detainees as proteges of Khalid Sheikh Mohammed and another top al-Qaida official, and trusted by both bin Laden and his top lieutenant, Ayman al-Zawahri.

But they only knew the men by noms de guerre -- or terror aliases -- and were thwarted by al-Qaida operatives from finding out their true names. The first break came four years ago, the officials said, when they found out the men's true names. Then in 2009, they discovered the areas in Pakistan in which they operated.

In September, the officials said, U.S. intelligence identified a compound in Abbottabad -- not far from Islamabad -- that was owned by the two men. It had been constructed in 2005, and had all the telltale signs of a possible hideout for bin Laden.

It was owned by trusted associates. It had high walls, and high security -- including a 7-foot wall protecting a terrace at the top of one of the structures. Entrance was through one of two guarded gates. Trash was burned inside the compound instead of being left on the street for pickup. When built, it had been both larger than other dwellings, and more isolated.

It was worth more than $1 million, but there was no record of phone or Internet service. Officials said they also had evidence that a third family matching the size and structure of bin Laden's family appeared to be living there, along with the two brothers and their families.

"It was custom-built to hide someone of significance," one official said.

Beginning last September, President Barack Obama personally ran five National Security Council meetings to assess the value of the new intelligence and the feasibility of acting on it. The raid itself took 40 minutes.

One of the helicopters used suffered mechanical difficulties and had to be destroyed.

The officials said that bin Laden "did resist the assault force and was killed in a firefight as our operatives came into the compound."

Also killed: the two couriers, a man believed to be an adult son of bin Laden and a woman who officials said was used as a shield by one of the men.

Planning for the raid was not shared with the Pakistani government because of the need for operational security, officials said.