On the morning of Sept. 11, 2001, while the world watched the horror of jetliners smashing into the World Trade Center, the Pentagon and a field in Pennsylvania, Zacarias Moussaoui sat in a jail cell -- possibly withholding information that could have averted the attacks.
Moussaoui -- the only person charged in the United States for having direct knowledge of the Sept. 11 attacks -- goes before a jury today in a federal courtroom in Alexandria, Va., to determine whether he knowingly lied or covered up knowledge of the attacks. If he is found guilty, the jury will then decide if he should be executed or face life in prison
Moussaoui was arrested in August 2001 and held on immigration violations. A self-professed al Qaeda member, Moussaoui pleaded guilty to six counts of conspiracy in April 2005, for knowing about al Qaeda's Sept. 11 plans and agreeing to participate in the attacks.
The government's prosecution will focus on whether the attacks could have been prevented had Moussaoui told FBI agents about al Qaeda's plans.
Previously, Moussaoui has said he was not part of the 9/11 plot but that he was tasked to take part in a second wave of attacks destined to hit the White House. At his plea hearing in April 2005, Moussaoui said, "I was being trained on the 747-400 to eventually use this plane ... to strike the White House, but this conspiracy was different conspiracy than 9/11."
The trial is expected to last up to three months and will recall many of the tragic stories of 9/11, with more than 150 witnesses expected to testify.
Justice Department prosecutors handling the case intend to identify in photographs the nearly 3,000 victims killed during the attacks and have said in court filings that they will call 45 victims to testify against Moussaoui.
The court in Virginia has set up a closed-circuit TV feed for the victims' families to view the trial in Alexandria and at federal courthouses in Boston; Long Island, N.Y.; Newark, N.J.; Manhattan; and Philadelphia. About 530 family members have signed up to attend the trial at these locations.
The government will also call numerous expert witnesses, FBI counterterrorism officials and people who Moussaoui knew in the United States -- including his former roommate, Hussein Al Attas, who has agreed to testify against Moussaoui. Al Attas pleaded guilty in 2002 to lying to FBI agents about his time with Moussaoui. He was arrested with Moussaoui in Minnesota.
The defense intends to show how a series of missed opportunities by the government failed to prevent the attacks, and that Moussaoui's lies did not keep the government from linking events that may have averted the plot.
In the summer of 2001, U.S intelligence agencies began to receive and collect various threat reports about planned al Qaeda attacks.
President Bush was briefed on Aug. 6, 2001, with a report called "Bin Laden Determined to Strike in the U.S." The report noted the CIA and FBI were investigating claims that bin Laden supporters were in the U.S. planning attacks with explosives.
Numerous investigations by congressional committees and the 9/11 Commission have examined the troubled relationship between the FBI and the CIA and how they missed opportunities to detect and potentially prevent the attacks.