Terror probe widens to Tsarnaev’s buddies

Federal investigators are widening their net as they dig deeper into the lives of suspected Boston Marathon bombers Tamerlan and Dzhokhar Tsarnaev.

Azamat Tazhayakov, Dias Kadyrbayev and Robel Phillipos have been jailed on charges that they tried to throw investigators off Dzhokhar Tsarnaev's trail, investigators announced Wednesday.

Former Homeland Security Secretary Michael Chertoff says investigators will be trying to figure out if there are any other plots, as well as if the three friends were involved in any of the preparation for the bombing.

“Were there connections that the Tsernaev’s had to people in the U.S. who might have been facilitators?” asked Chertoff.

“Were they trained in Russia? Were they inspired in Russia or in Chechnya?”

Chertoff told CNN that many of the plots he uncovered as Homeland Security Secretary involved a component of individuals going overseas to train with foreign organizations and bringing that knowledge back home.

The region of Dagestan, said Chertoff, has a history of radicalizing individuals and that “obviously there was a failure” when it came to intelligence gathering surrounding the older brother Tamerlan’s visit to Russia.

Chertoff told CNN that Russia has a history of cooperation with the U.S. on counterterrorism investigations.

In his experience, Chertoff says, if a country notifies U.S. authorities of a specific individual two times, the information should be taken seriously.

“You’ve got to drill into it,” Chertoff said of the initial Russian request for information on Tamerlan Tsarnaev.

“That’s frankly what the jobs of the security folks every single day is, to really kick the tires and make sure they’re extracting every bit of information they can.”