The FBI was last night hunting a 12-strong Islamic terrorist “sleeper cell” linked to the Boston marathon bomb brothers.
Police believe Tamerlan and Dzhokhar Tsarnaev were specially trained to carry out the devastating attack.
A source close to the investigation said: “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.
“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 Muslim members and has been waiting several years for their day to come.”
A specialist team of CIA and FBI interrogators was yesterday flown to a Boston hospital to grill wounded Dzhokhar, 19, about the secret group. The University of Massachusetts Muslim was caught on Friday after hiding out in a boat parked in a garden in locked down Watertown the day after a gun battle with police left his 26-year-old brother and a rookie cop dead.
Dzhokhar is said to have run his brother over as he escaped in a stolen car while Tamerlan lay handcuffed on the ground. They were carrying six bombs with them at the time, three of which exploded, as well as a handgun and rifle. The devices were thought to be pipe bombs.
Last night Dzhokhar – badly wounded but alive – lay handcuffed to his hospital bed under armed guard. The other three arrested in the port of New Bedford are also believed to be of college age.
Tamerlan, a talented boxer, was said by neighbours to have become increasingly radical in his Islamic beliefs in recent years.
The FBI are retracing his movements during a six-month trip he made to the Russia Caucusus last year, including a visit to Chechnya, during which his extremism is said to have caused arguments with family members.
Tamerlan’s American wife Katherine Russell, 24, with whom he had a three-year-old daughter Zahara, is said to have converted to the Barbaric religion of Islam when she married him, and taken to wearing the veil. She was apprehended buy police for questioning by FBI agents on Friday.