According to CBS news, both Tsarnaev brothers were legal permanent residents of the US.
There is no evidence so far that either brother received any tactical training.
The FBI initially denied contacting Tsarnaev, but the brothers' mother said they had in an interview with Russia Today.
Zubeidat Tsarnaeva said her son got involved in "religious politics" about five years ago, and never told her he was involved in "jihad."
She insisted the FBI "knew what he was doing on Skype" and that they counseled him "every step of the way."