FBI interviews Boston suspects' parents in Russia

The suspects' mother, Zubeidat Tsarnaev, said her eldest son, Tamerlan, was “framed” by U.S. authorities. The 26-year-old died after a shootout with law enforcement officials last Friday.

“He was 'controlled' by the FBI, like, for three to five years,” Tsarnaev told Kremlin-funded Russia Today. “They knew what my son was doing, they knew what sites on the Internet he was going to.”

President Vladimir Putin has pledged his country's help after the attack. President Obama thanked him in a telephone call Friday evening.

“President Putin expressed his condolences on behalf of the Russian people for the tragic loss of life in Boston,” according to a White House summary of the call. “President Obama thanked President Putin for those sentiments, and praised the close cooperation that the United States has received from Russia on counter-terrorism, including in the wake of the Boston attack.

“The two leaders agreed to continue our cooperation on counter-terrorism and security issues going forward.”