On Thursday, the Associated Press reported Russell had hired New York lawyer Joshua Dratel to represent her. Dratel has represented a number of accused terror suspects, including at least on Guantanamo detainee
Russell has not been charged with any crime, but has met repeatedly with investigators from the FBI.
McCaul also suggested Friday that Tsarnaev's parents could have been responsible for his radicalization.
"With respect to the mother, I think she radicalized him. Uh, and the father, I think there's a reason why he has declined his trip to come back into the United States," McCaul said.