"I am 100 percent sure that this is a setup," she told Russia Today. "My two sons are really innocent and neither of them have ever talked about what they said now."

She added later, however, that her older son, Tamerlan, got involved in "religious politics" five years ago. And she appeared to suggest that she had been contacted by the FBI about Tamerlan prior to the marathon bombing attacks.

"He was controlled by the FBI for five years," she said."They knew what my son was doing, they knew what sites on the Internet he was going [to], they used to come...and talk to me...they were telling me that he was a serious leader and they were afraid of him."