The White House has strongly defended the FBI for its past investigations against the Boston bombing suspect Tamerlan Tsarnaev and denied the allegations of lawmakers that federal agency dropped the ball when it was informed by the Russians that he was radicalised.
29, died last Thursday in a exchange of fire with police in Boston neighbourhood.
He is suspected to be mastermind of the April 15 blasts that killed three people and injured 264 others.
His accomplice and younger brother, Dzhokhar, 19, has been arrested and is being treated in a Boston city hospital.
"Tamerlan Tsarnaev did ping in our systems when he travelled.
"But we also know that the FBI did a thorough investigation in 2011 and did not find any terrorism activity, foreign or domestic," the White House press secretary Jay Carney told reporters at a news conference on Wednesday.
He was responding when asked as to why the FBI did not follow the Boston bombing suspect when it was alerted by the Russians about his radicalisation.
"You know, as the (US) President made clear when he spoke before you on Friday night, he wants every agency involved in this to do a broad investigation into what happened, what we knew, what inspired and motivated these two individuals, and the steps that they took that led to the terrorist attacks in Boston a week ago Monday.
"That process needs to take place, and it's being undertaken now in an investigation led by the FBI and a prosecution, obviously, led by the Justice Department," he said.
FBI, he said, took action in 2011 in response to information provided to them by a Russian government, and the conclusions that they reached then and the nature of the investigation they conducted then.
"Beyond that, I think we need to let the investigation unfold and make assessments when we know all the facts," Carney said.
The US Embassy in Russia, he said, has sent a team down to Dagestan to interview the Tsarnaevs' parents, and that is part of an investigation into both the broad question about these two young men and what motivated them and their past and their history, and also the specific visit that the elder brother made last year.
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