The older of the two top suspects in the Boston bombings this week had been under FBI surveillance for at least three years, his mother said in an interview with Russian state television broadcaster RT.
Tamerlan Tsarnaev (26), who was killed in a shootout with police a day before his brother's capture yesterday, was accessing extremist sites and was closely monitored by the FBI, Zubeidat Tsarnaeva said in a phone interview in English from Makhachkala, in the southern Russian region of Dagestan, posted on the channel's website.
"My son would never do this," Ms Tsarnaeva said. "He was controlled by the FBI for three to five years, they knew what my son was doing, they knew what actions, on what sites on the internet he was going," she said. "So how could this happen? They were controlling every step of his."
Temerlan and his brother Dzhokhar (19) are accused of carrying out bombings near the finishing line of the Boston Marathon on April 15th that killed three people and injured more than 170.
Their mother insisted they were innocent.
"My two sons are really innocent and I know that neither of them never, never, have talked about whatever they're saying about now," she told Russian media.
She said "nobody talked about terrorism" in their house, and said she believed her sons were not involved in it.
Ms Tsarnaeva said her sons used to call her every day to ask how she was, and recalled them saying: "Mama, we love you. Mama, how are you? We miss you."
She added: "It's impossible, impossible for both of them to do such things, so I am really, really, really, really telling that this is a set-up."
She said her sons did not keep secrets from her, and said: "If there is anyone who would know it would be me."