WASHINGTON — Russia has informed the United States that it knew of no contact between Tamerlan Tsarnaev and any known terrorist groups during his six-month trip to Dagestan in 2012, according to an official who attended a closed-door Senate briefing Thursday morning by top counterterrorism officials.
Russia provided the information to US authorities five days ago, the official said.
The statements could bolster theories that Tsarnaev and his younger brother, Dzhokhar Tsarnaev, were acting on their own when they allegedly planted two bombs near the finish line of the Boston Marathon on April 15, and not at the behest of any foreign terror groups.
Other officials have said the Tsarnaev brothers expressed interest in radical Islam and terrorist activity over the Internet.
Officials at the Thursday briefing told senators that warnings from Russia to the United States in 2011 about Tamerlan Tsarnaev also advised the FBI that “you need to watch the mother, too,’’ according to the official.
However, Tsarnaev’s mother — Zubeidat Tsarnaeva — was not placed on US terror watchlist, as her son was, an indication that the FBI did not consider her a threat, the official said.
Zubeidat Tsarnaeva has not been linked to any criminal activity related to last week’s Boston Marathon bombing.
“The letter was about him, but they suggested the mother may be involved too,’’ the official said.
Investigators also linked Tamerlan Tsarnaev’s phone records to two other phone numbers for people who had been investigated for terror, the official said. But the two other terror cases were closed. It’s not clear when the FBI discovered those phone links or when those cases were closed.
Senators were briefed on the investigation into the April 15 Boston Marathon bombings on Thursday morning by top counterterrorism officials, including FBI Deputy Director Sean Joyce.
Tamerlan Tsarnaev died after a shootout with police on April 19. Dzhokhar is recovering at Beth Israel Deaconess Medical Center after being captured the next day in Watertown. He has been charged in the bombings, which killed three people on the sidewalk on Boylston Street and injured more than 250. If convicted he could recieve the death penalty.