NEW : Senators say no indication yet that the FBI `` dropped the ball '' NEW : Republican senators cite failure of federal agencies to share information . Legislators question the FBI handling of bombing suspect FBI . The Tamerlan Tsarnaev investigated FBI 2010 before the Chechnya Marathon bombing .
NEW : Senators say no indication yet that the FBI `` dropped the ball '' NEW : Republican senators cite failure of federal agencies to share information . Legislators question the FBI handling of bombing suspect Tamerlan Tsarnaev . The FBI investigated Tsarnaev two years before the Boston Marathon bombing .