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STORY: :: File

:: U.S. News and World Report

The accused mastermind of the September 11 attacks Khalid Sheikh Mohammed and two of his accomplices– all held at the U.S. military prison at Guantanamo Bay– have agreed to plead guilty.

The Pentagon announced the development on Wednesday without elaborating on the plea deals.

However, a U.S. official, speaking on condition of anonymity, said the deals almost certainly involved guilty pleas in exchange for taking the death penalty off the table.

Mohammed is accused of masterminding the plot to fly hijacked commercial passenger aircraft into the World Trade Center in New York City and into the Pentagon on September 11, 2001.

The attacks killed nearly 3,000 people and plunged the United States into what would become a two-decade-long war in Afghanistan.

Mohammed is the most well-known inmate at the detention facility in Guantanamo Bay in Cuba.

The prison was set up in 2002 by then-U.S. President George W. Bush to house foreign militant suspects following the September 11 attacks.

:: File

Its population grew to a peak of about 800 inmates before it started to shrink.

Only 30 inmates remain today.

Mohammed’s interrogations have long been the subject of scrutiny.

A 2014 Senate Intelligence Committee report on the CIA's use of waterboarding and other QUOTE "enhanced interrogation techniques" said that Mohammed had been waterboarded at least 183 times.