Many are wondering why the FBI overlooked the potential danger posed by now-deceased bombing suspect Tamerlan Tsarnaev in 2011 after they interviewed him. According to reports, the bureau failed to find any incriminating evidence of terrorist ties.

As first reported by CBS News correspondent Bob Orr, the FBI interviewed Tsarnaev, the elder brother of at-large bombing suspect Dzhokhar A. Tsarnaev, at the request of a foreign government to see if he had any extremist ties, but failed to find any linkage.

Both Tsarnaev brothers were legal permanent residents of the U.S. There is no evidence so far that either brother received any tactical training.

The FBI initially denied making contact with Tsarnaev, but his mother said to Russia Today that the FBI had in fact spoke with her son, saying he became involved with “religious politics” around five years ago. :

“They used to come [to our] home, they used to talk to me … they were telling me that he was really an extremist leader and that they were afraid of him,” Tsarnaeva said. “They told me whatever information he is getting, he gets from these extremist sites… they were controlling him, they were controlling his every step… and now they say that this is a terrorist act!”

The FBI insists to CBS that they took all the required steps that were permissable under the law. However, around the same time the bureau interviewed Tsarnaev, changes in the FBI training manual took place as well. The FBI’s own departmental counter-terrorism analytic lexicon was purged of key words that could reference Islamic terrorism. Words like Muslim, Islam, Muslim Brotherhood, Hamas, and sharia were not mentioned once in the FBI’s counter-terrorism lexicon afterwards.

The FBI initially denied the existence of the document in 2012 until PJ Media’s Patrick Poole posted the unclassified doc in May of that year. Congressman Louie Gohmert (R-TX) took the issue to the House floor and excoriated the administration for allowing the changing of the training manual to happen.

Congress is now concerned that Tsarnaev slipped through the fingers of law enforcement early on. Congressman Mike McCaul (R-TX) , Chairman of the House Homeland Security Committee, told CNN that he finds it “disturbing” the late bombing suspect was “on the FBI’s radar screen and they let him out of their sights, then that’s an issue, certainly, for me.”