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FBI Director Robert S. Mueller III conceded on Thursday that a lack of formal communication within the agency prevented investigators from alerting Russian authorities that Tamerlan Tsarnaev had returned to Russia before the Marathon bombing, information that Russians have asserted could have averted the act of terrorism.
Mueller also told a congressional panel that the government’s recently revealed surveillance techniques helped spur an investigation of an associate of Tsarnaev, Ibragim Todashev, 27.
Todashev was shot to death by an FBI agent in Florida last month during an interview related to his and Tsarnaev’s role in a Waltham triple homicide, but Mueller declined to comment on the circumstances during Thursday’s hearing, citing an ongoing investigation.