story. The hunt underway in Russia tonight. Authorities chasing a big lead on terrorism. Word that a black widow suicide bomber may have been spotted on the grounds near the olympic site. Also, what... See More
story. The hunt underway in Russia tonight. Authorities chasing a big lead on terrorism. Word that a black widow suicide bomber may have been spotted on the grounds near the olympic site. Also, what about the 15,000 Americans who go to watch the olympics live. ABC chief investigative correspondent, Brian Ross, on keeping them safe. Reporter: Tucker Fredericks on the right, is one of the fastest Americans on ice. And when the 29-year-old on the left qualified for the U.S. Olympics speed skating team last month it was a big moment for him and his family, who have backed him for so many years. But today, his parents in jamesville, Wisconsin, said, they will not be going to sochi. Their son asked them not to go, because of his concern there could be a terror attack at the olympics. He wanted us to stay home so he wouldn't have to worry about us. One less thing to be concerned about. Reporter: And the concern is growing tonight, as Russian authorities come up short in their efforts to find a possible female suicide bomber. This 22-year-old so-called black widow, believed to be already in sochi, preparing to act. They have the idea that they are using terrorism as a warm of war. Reporter: The alleged female suicide bomber being sought in sochi, was reportedly last seen in the downtown area of the city, near city hall. And she is likely not alone, according to a top U.S. Official who toured sochi today. My concern is there's many more of them. What I'm concerned most about this particular case is that she broke through the perimeter and got into sochi. Reporter: Russia continues to insist it has security issues in hand. And counterterrorism officials in Moscow said today, they had killed one of the leaders of the islamic terror groups targeting sochi in this military raid conducted over the weekend in dagestan. Brian's here. What about the 15,000 Americans, the families, the friends, the tourists? Reporter: That's just too many according to security experts for two ships in the black sea to handle. We did learn today that president Putin talked to president Obama. And president Obama offered new U.S. Assistance, which could include equipment that could jam roadside bombs. Rybrian Ross, following this story.
This transcript has been automatically generated and may not be 100% accurate.