The FBI investigated but found no evidence of extremist activity and closed the case.

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The FBI investigated, but found no evidence of extremist activity, FBI Director Robert Mueller told a Senate committee.

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But the FBI found no evidence of extremist activity and closed the case.

CNN: Source: Russia withheld details about Tsarnaev

The FBI investigated, but found no evidence of extremist activity, FBI Director Robert Mueller reiterated Thursday during a Senate Appropriations Committee hearing.

CNN: Suspect: Boston bombing was payback for hits on Muslims

The project is dedicated to monitoring hate groups and extremist activity in the U.S. He joined us from his office in Montgomery, Alabama.

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