Najibullah Zazi in Contact with Al Qaeda's Leader

According to the Associated Press, Najibullah Zazi, 24, had contact with Al Qaeda's leader in Afghanistan, Mustafa Abu al-Yazid, who has been reported to have worked closely with Osama bin LadenOsama bin Laden. Al-Yazid is known as a top of the list terrorist leader.

Zazi's suspected of plotting to bomb New York City's transit system. Through a middleman, he was able to get in touch with Al-Yazid.

Officials have said Zazi's involvement with the Al Qaeda leader was one of the most serious threats to the United States since the 9/11 attacks. The attack was possibly scheduled for the eighth anniversary of the September 11th attacks.

On a trip to Pakistan in 2008, prosecutors say Zazi admitted he received instructions from Al Qaeda operatives on subjects such as weapons and explosives.

Zazi, an Afghan immigrant, moved to Queens as a teenager. He became an airport shuttle driver in Denver earlier this year. He is being held in New York while he awaits trial. He denies ever receiving any terror training.

Federal agents say they found nine pages of handwritten bomb-making instructions in Zazi's e-mail. The directions to make explosives of hydrogen peroxide and flour are similar to the bombs used by terrorists to bomb the London subway in 2005, killing 52 people.

Counter-terrorism expert Seth Jones said Al-Yazid took part in the 1981 assassination of President Anwar Sadat. He served as Osama bin Laden's accountant when he moved to Sudan in 1991 and became the leader's confidant.