The Warning Before the Attack

July 8, 2005 — -- A captured al Qaeda leader warned United States interrogators that the London mass transit system was a likely target for an attack.

U.S. officials tell ABC News that Al Faraj al Libbi, captured in Pakistan this past May, detailed plans to target London and selected U.S. cities, but did not specify a time for the attacks.

This comes as both British authorities and U.S. intelligence officials said that they were no longer dismissing the claim of responsibility posted on the Web by al Qaeda of Europe, a previously unknown group.

It's a move with which Fawaz Gerges, chair of international studies and Middle Eastern affairs at Sara Lawrence College, agrees: "It has the flavor, the rhetoric of al Qaeda. I've read it closely. I tend to believe it's an authentic statement."

In London, the investigation continued. Three passengers on the targeted double-decker bus told police they saw a tall, olive-skinned man in his 20s fiddling with a package just before the explosion. His body and belongings are now at the center of the investigation.

"You probably have your first major clue," said Jack Cloonan, a former FBI agent. "You've got the person who delivered it, and that person has a trail. Whether it's by face or fingerprints or DNA, now the investigation picks up speed dramatically."

U.S. authorities have also been told that British police detonated the two packages they found yesterday and discovered that they were not bombs but only two abandoned parcels.