The bombings of a train station and an electric trolleybus in late December killed 34 people and heightened security fears ahead of the Sochi Winter Olympics, which begin on Friday.
Russia's counterterrorism agency last week named the suspected bombers and said they were members of a terrorist group based in Dagestan, a republic in Russia's North Caucasus region that is the center of an Islamic insurgency. Two suspected accomplices have been arrested.
On Wednesday, a spokesman for the
Russian investigative agency said the militant killed in a shootout in Dagestan
may have been involved in training the bombers and sending them to Volgograd.
brothers identified as Magomednabi and Tagir Batirov, suspected of helping send the bombers to Volgograd, were detained in Dagestan last week, according to Russia's National Anti-Terrorism Committee, which said the
investigation was continuing.
posted on the Internet two weeks ago by a group identifying itself as Vilayat
Dagestan featured what it said were the Volgograd
bombers donning explosive belts and warning President Vladimir Putin to expect a "present" at the Olympics.
Russia's security forces launched a major security crackdown on suspected militants in the southern region following the attacks, raiding various homes and buildings around Sochi. Early in January officials claimed to have killed seven militants -- including an alleged "black widow" female would-be suicide bomber -- in a raid in Dagestan.
On Tuesday, a top U.S.
counterterrorism official said there were "a number of specific threats" aimed at the Games in Sochi, with the greatest danger
coming from the Caucasus Emirate -- the umbrella group believed to be behind most of the violence in the region.
Matthew Olsen, director of the
National Counterterrorism Center, told Congress the U.S. and
Russia were tracking threats of "varying degrees" of credibility. He
said potential attacks seem more likely outside the venues for the games, in the area or region around Sochi.
Speaking at a news conference in Sochi last Thursday, Alexey Lavrishev insisted there were no indications from Russian intelligence, or the "information of our partners" suggesting a direct threat to the event.