Background: Al-Qaida Mastermind, Khalid Shaikh Mohammed

KWAME HOLMAN:

Pakistani and U.S. Agents today analyzed computers and documents from this residence outside Islamabad, where CIA and local officials arrested Khalid Shaikh Mohammed Saturday. Early reports said he was in U.S. custody, but Pakistani officials indicated otherwise.

AZIZ AHMED KHAN, Foreign Office, Pakistan:

As far as the present position is concerned, he is still in Pakistan. He is being interrogated by our authorities.

KWAME HOLMAN:

Mohammed, the head of operations for al-Qaida, is thought to be 37 or 38 years old. Born in Kuwait, he studied engineering at two North Carolina colleges in the mid 1980s. Soon after, Mohammed fought alongside Osama bin Laden in the Afghan war against the Soviets.

He's considered a master of disguise and fake identity. The uncle of a man convicted in the 1993 World Trade Center bombing, Mohammed is directly linked to attacks on U.S. embassies in Africa, the USS "Cole" explosion off of Yemen, last year's bombing of a synagogue in Tunisia that killed 19, and the kidnapping and murder of American reporter Daniel Pearl.

In 1996, a U.S. court convicted Mohammed in absentia of involvement in a plot to blow up U.S. Commercial jets over the pacific, and to crash a plane into CIA headquarters. As for Sept. 11, bin Laden's number three man told the al Jazeera network last year he helped devise what he called "Holy Tuesday." At the White House, spokesman Ari Fleischer hailed the arrest.

ARI FLEISCHER:

The president expresses his deep appreciation and gratitude to Pres. Musharraf and to the government of Pakistan for their efforts this past weekend that led to the capture of Khalid sheik Mohammed, the mastermind of the Sept. 11 attack. This a very serious development and a blow to al-Qaida.

KWAME HOLMAN:

Separately, homeland security Sec. Tom Ridge said his agency raised the terror alert level last month in part because of a plot involving Mohammed. The alert level was lowered last week.