Ahmed, a naturalized U.S. citizen born in Pakistan, was charged with attempting to provide material support to a designated terrorist organization, collecting information to assist in planning a terrorist attack on a transit facility, and attempting to provide material support to help carry out multiple bombings to cause mass casualties at D.C.-area Metrorail stations. If convicted, he faces a maximum penalty of 50 years in prison.

He was arrested by the FBI early Wednesday morning and is scheduled to make his first appearance before a federal judge in the afternoon.

According to the indictment, from April through Oct. 25, Ahmed attempted to assist others whom he believed to be members of al- Qaida in planning multiple bombings to cause mass casualties at Metrorail stations. He allegedly agreed to watch and photograph Metrorail stations in Arlington, Va., to obtain information about their security and busiest periods, and participated in surveillance and recorded video images of the Metrorail stations. He later handed video and photos to his contact, and agreed to assess the security of two Metrorail stations in Arlington as locations of terrorist attacks.

He later provided diagrams he drew of three Metrorail stations in Arlington and provided suggestions as to where explosives should be placed to kill the most people in simultaneous attacks planned for 2011.

This case is being investigated by the FBI's Washington Field Office Joint Terrorism Task Force, which includes 35 agencies in the Northern Virginia and Washington, D.C., metropolitan area.