The FBI says it interviewed Tamerlan Tsarnaev, one of two Boston Marathon attack suspects, two years ago but failed to find any incriminating evidence.

CBS News reports a foreign government requested more information to see if Tsarnaev had any extremist ties.

It’s likely it was Russia trying to find out if Tsarnaev had ties to Chechen extremists, according to correspondent John Miller.

CBS says the FBI initially denied contacting the older brother, but his mother, Zubeidat Tsarnaeva, tells Russia Today otherwise. She says her son became involved in “religious politics” about five years ago.

Tsarnaev died at a Boston hospital of possible blast injuries and gunshot wounds after a shootout with police in Watertown early Friday morning.