Source: FSB Suspects Russian Bus Bombing Meant to Embarrass Putin

Oct. 23, 2013 — -- Russian intelligence suspects the female suicide bomber who killed six people on a bus in the southern city of Volgograd Monday did so in an effort to embarrass Russian President Vladimir Putin and undermine his government's promises that the 2014 Olympics in Sochi, Russia will be secure, according to a Western official briefed on the case.

The source said the Russian FSB, the successor to the KGB, believes, at least based on preliminary evidence, the bomber intended to travel to Moscow but detonated the bomb early, apparently having gotten nervous after changing buses in Volgograd, formerly known as Stalingrad. Russian authorities said Tuesday the bomber had purchased a bus ticket from her home in the southern Russian republic of Dagestan to the Russian capital of Moscow.

The Western source said Russian government agents are cracking down in Dagestan in an attempt to find the bomber's husband, who local authorities reportedly said is an explosives expert in the violent Islamist insurgency based in the North Caucasus. The widower is thought to be "savvy" and on the move, the source said.

Terrorism experts told ABC News Tuesday that the bus bombing could be an opening salvo in a new series of plots potentially targeting civilians up to and during the Sochi Olympics.

No group has claimed responsibility for the attack yet, but Robert Pape, Director of the University of Chicago's Chicago Project on Security and Terrorism, said Tuesday he has no doubt the bombing was the work of the Chechen insurgency, led by Russia's most wanted man, Doku Umarov. Pape cited the woman's reported marriage to the bomb maker, the widespread use of female suicide bombers -- called "black widows" -- by the insurgency and the fact that generally speaking, no other group conducts significant terrorist attacks of that type in the region.

"Those aren't just loose correlations, there's very little reason to doubt," Pape said.

In July, Umarov released a video online calling on his followers to use "maximum force" to put a stop to the Games, which he said was "Satanic dancing on the bones of our ancestors."

Sochi lies on the Black Sea near Russia's southern border with Georgia, 300 miles west of the Chechen capital of Grozny, which is nearly a third of the distance from Sochi to Russia's capital in Moscow.

READ MORE: Olympic Security Fears After Russia Bus Bombing

"Show me an event, any major event in the world, where security is not an issue... It's no different for us," Dmitry Chernyshenko, a member of the Sochi 2014 Organizing Committee, said in June 2012, before acknowledging the proximity of the Games to the traditional home for rebel leaders. "You know the situation in general is not easy in the world. That is why the host nation should be ready for any scenario. I know everything that is needed will be there to protect the Games."

ABC News' Lee Ferran contributed to this report.