Sources close to the FBI investigation claim that Tamerlan and Dzhokhar Tsarnaev did not act alone and were part of a 12-man terror sleeper cell.
According to a source, the FBI was working furiously to track down the cell amid concerns that further attacks on American soil are being planned and carried out.
On Saturday afternoon, two 19-year-old men from Kazakhstan named by neighbors by their first names Azmat and Diaz and thought to be friends of Tamerlan and Dzhokhar Tsarnaev were arrested – as it was revealed the pair drove around in a black BMW with vanity plates that read “Terorrista#1”.
“We have no doubt the brothers were not acting alone. The devices used to detonate the two bombs were highly sophisticated and not the kind of thing people learn from Google,” said the source to the UK’s Daily Mirror.
“They were too advanced. Someone gave the brothers the skills and it is now our job to find out just who they were. Agents think the sleeper cell has up to a dozen members and has been waiting several years for their day to come.”
However, the Boston Mayor Tom Menino says the briefings he has been privy to assure him that the suspects in the Boston Marathon bombing acted alone.
Tom Menino told ABC’s This Week that he agreed with the decision to lock down Boston all day Friday, based on what officials knew at the time.
He did admit though that a pipe bomb has been found at another location and that another person has been taken into custody, although at this time he would not elaborate.
Azmat and Diaz, who are said to be friends with Dzhokhar Tsarnaev were taken into custody again on Saturday.
This time the two foreign nationals were arrested over alleged immigration violations in the Massachusetts town, New Bedford, where police say the surviving suspect, Dzhokhar Tsarnaev, may have once lived.