The FBI says it had interviewed one of the suspects in the Boston Marathon bombing as far back as two years ago.
Tamerlan Tsarnaev was flagged up in 2011 by Russia over alleged links to radical Islam.
He was killed in a shoot-out with police on Friday. His bother, Dzhokhar was found hiding in the backyard of a home in the Watertown area of Boston and is in critical condition.
Before arriving in the US, the Tsarnaev brothers went to school in the republic of Dagestan, where their parents have since returned to live.
Al Jazeera's David Chater reports from Dagestan's provincial capital, Makhachkala.