Federal law enforcement officials are actively investigating the possibility that the Boston bombers were known to the government’s terror-trackers, MailOnline understands.
Any inquiry into the marathon bombing will look into whether agents could have taken action – but didn’t – to prevent the Tsarnaev brothers from obtaining the explosives that killed 3 and wounded 173 others.
CBS News reported Friday evening that two years ago, the FBI interviewed the elder brother Tamerlan Tsarnaev, 26, who was killed in Thursday night's dramatic shootout. The feds reportedly spoke to him at the request of an unspecified foreign government, but couldn't establish that he had ties to terrorist radicals.
Tamerlan left the United States in January 2012 for Russia and returned in mid-July, according to records uncovered by NBC in New York.
But an official inside the Department of Homeland Security with knowledge of federal law enforcement activities in Massachusetts has claimed to MailOnline that Tamerlan was on the radar screen of agents in Boston between his return to the U.S. and the end of the fall.
Inquiry: After the drama has subsided, federal officers will be scoruing records to see if there was any way the bomber could have been stopped. Tamerlan Tsarnaev, left, 26, and his brother Dzhokhar Tsarnaev, 19, right
Under the radar: Once source told MailOnline in an unconfirmed claim that law agencies received tips from inside a local mosque in 2012 about young Muslims who were becoming radicalized. Tamerlan Tsarnaev was allegedly one of those.
The source, who has been contradicted by other officials, said that in 2012 federal law enforcement received tips from inside a Boston mosque about young Muslims, including some converts, who were becoming radicalized into anti-American zealots as their knowledge of their religion grew.
Tamerlan was allegedly one of those radicals, and attracted the attention of an informant working with an agency attached to the Boston-area Joint Terrorism Task Force (JTTF). That informant communicated observations about the man to a government handler, the source said.
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A second source, formerly assigned to a U.S. JTTF, confirmed to MailOnline that ‘there is some very quiet discussion in the Boston JTTF about this.’
The formerly JTTF-affiliated agent said that right now, ‘These guys are more interested in catching the younger terrorist alive, and interrogating him, than in worrying about what the different agencies knew and when they knew it.’
Urgent: The priority of law enforcement agencies is to find the fugitive brother before questions are asked if anything could have been done soomer
The Homeland Security source told MailOnline that the FBI in Boston now believes Tamerlan was receiving assistance from an 'organized radical element' in Massachusetts. And agents are now reviewing at least one report from inside a mosque to see if they can identify Tamerlan’s associates in Boston's Muslim community.
Law enforcement at the federal level has 'practically nothing' on Dzhokhar, Tamerlan's younger brother,that source claimed.
The Associated Press reported late Friday evening that Dzhokhar was in police custody.
Both sources spoke on condition of anonymity because they are not permitted to talk about ongoing investigations.
Special Agent Greg Comcowich, the FBI's media coordinator in Boston, would not confirm the report.
'I'm going to have to go with my standard response,' Comcowich told MailOnline. 'We don't confirm or deny investigative activities.'
'Unfortunately,’ he added, 'I don't have time to research this right now.'
A spokesman in the Department of Homeland Security’s media office also would not comment on the reports.
But MailOnline's source from inside that agency said the older Tsarnaev brother turned up in a tip from an 'undercover asset.'
Ultimately Tamerlan was allegedly deemed 'a low priority' and federal law enforcement 'did not designate them [the brothers] as suspects or persons of interest in any crime.'
They also were not flagged for deportation by U.S. Immigration and Customs Enforcement.
The Tsarnaevs emigrated to the U.S. and were granted asylum in 2002. Dzhokhar, now 19, received his green card two years later. He became a naturalized U.S. citizen on Sept. 11, 2012.