According to Newsday,

British police and intelligence officials have launched a nationwide manhunt for a man identified as a likely bomb maker in last week’s London attacks, who was seen on a security tape with the four suspected bombers, according to a U.S. official.

“They know who No. 5 is,” said the official, who has access to substantial intelligence flowing from the bomb investigation but asked to not be identified.

The man was pictured on a closed-circuit security tape with the four bombers just before they entered London’s Underground on July 7 with backpacks the police believe contained bombs. He is British and dark-skinned, apparently of Caribbean descent, the official said.

A video camera in King’s Cross Station in North London captured the five men huddling together at about 8:30 on the morning of the bombings. Then, said the official, “The four goons [suicide bombers] went their way, and No. 5 went his.”