From security analysts Raelynn Hillhouse and her blog  The Spy Who Billed Me:

Sources in the intelligence community tell me that after years of trying and one bureaucratically insane near-miss in Yemen,the US government killed OBL because a Pakistani intelligence officer came forward to collect the approximately $25 million reward from the State Department’s Rewards for Justice program.

The informant was a walk-in.

The ISI officer came forward to claim the substantial reward and to broker US citizenship for his family.   My sources tell me that the informant claimed that the Saudis were paying off the Pakistani military and intelligence (ISI) to essentially shelter and keep bin Laden under house arrest in Abbottabad, a city with such a high concentration of military that I’m told there’s no equivalent in the US.

The CIA and friends then set about proving that OBL was indeed there.  And they did.

Next they approached the chiefs of the Pakistani military and the ISI.  The US was going to come in with or without them.  The CIA offered them a deal they couldn’t refuse:  they would double what the Saudis were paying them to keep bin Laden if they cooperated with the US.  Or they could refuse the deal and live with the consequences:  the Saudis would stop paying and there would be the international embarassment…

The ISI and Pakistani military were cooperating with the US on the raid.

This is turning into a Tom Clancy novel