By Peter Finn and Greg Miller
Wednesday, October 27, 2010; 1:47 PM

Federal law enforcement authorities are investigating a nascent plot to carry out a series of terrorist bombings at stations in the Washington Metro system, according to intelligence and law enforcement sources.

The investigation is focused on a naturalized U.S. citizen, originally from Pakistan, who became the target of an undercover sting operation, the sources said. An administration official said the man drew the attention of law enforcement officials by seeking to obtain unspecified materials. The planned attack was not imminent, the sources said, speaking on condition of anonymity because the matter remains under investigation.

The man, Farooque Ahmed, 34, of Ashburn, Va., is believed to have conceived of the plot and planned to carry it out on his own, and it is not known how far he proceeded in his preparations...

Investigators say that starting in April, Ahmed began meeting with someone he thought was an al-Qaida courier who put him touch with others who asked him if he'd willing to do surveillance of stops on the subway system, known as the Metro.

Court documents say he watched and took picture at four stations, all in Virginia, and made sketches. He suggested putting bombs in rolling suitcases for simultaneous explosions in 2011, the FBI says. The three stations he picked out would help "kill as many military personnel as possible," according to court documents, apparently because of the use of those lines by people going to and from the Pentagon.

"At no time was the public in danger" as "the FBI was aware of Ahmed's activities from before the alleged attempt began and closely monitored his activities until his arrest," the department said.

The department said the indictment laid out this timeline of events:

* On April 18, "Ahmed allegedly drove to a hotel in Dulles, Va., and met with a courier he believed to be affiliated with a terrorist organization who provided Ahmed with a document that provided potential locations at which future meetings could be arranged."
* On or about May 15, "at a hotel in Herndon, Va., Ahmed allegedly agreed to watch and photograph another hotel in Washington, D.C., and a Metrorail station in Arlington, Va., to obtain information about their security and busiest periods."
* On or about July 19, "in a hotel room in Sterling, Va., Ahmed allegedly handed a memory stick containing video images of a Metrorail station in Arlington to an individual whom Ahmed believed to be affiliated with al-Qaida."
* On that same day, "Ahmed allegedly agreed to assess the security of two other Metrorail stations in Arlington as locations of terrorist attacks."
* On or about Sept. 28, "in a hotel room in Herndon, Ahmed handed a USB drive containing images of two Metrorail stations in Arlington to an individual whom Ahmed believed to be affiliated with al-Qaida."
* On or about Sept. 28, "Ahmed provided to an individual whom he believed to be affiliated with al-Qaida diagrams that Ahmed drew of three Metrorail stations in Arlington and provided suggestions as to where explosives should be placed on trains in Metrorail stations in Arlington to kill the most people in simultaneous attacks planned for 2011.