Feds targeting 'persons of interest' inside US in Boston bombing case

U.S. intelligence and law enforcement are pursuing several "persons of interest" inside the United States who may have played a part in the Boston Marathon bombings. 

"We still have persons of interest that we're working to find and identify and have conversations with," according to House Intelligence Committee chief Rep. Mike Rogers (R-Mich.).

"Clearly, that is where they went from the process of radicalization to ... violence," he said during an appearance on ABC's "This Week" on Sunday. 

"There is a lot that we just don't know," Rogers added. 

While the Michigan Republican would not comment on the number of individuals FBI and U.S. intelligence officials were looking for, he said several of those people are hiding out inside America's borders. 

"There are persons of interest in the United States," Rep. Dutch Ruppersberger (D-Md.), the House Intelligence panel's ranking member, said during the same interview. 

Brothers Tamerlan and Dzhokhar Tsarnaev are believed to have detonated two homemade bombs packed with shrapnel at the finish line of the Boston Marathon, killing three and maiming dozens.

House Homeland Security Committee Chairman Michael McCaul (R-Texas) said on Sunday the FBI is casting a "wide net" in the hunt for suspects who might have trained the brothers in how to make and detonate the bombs that tore through downtown Boston. 

"I think the experts all agree that there is someone who did train these two individuals," McCaul on Fox News Sunday.

FBI investigators have already interviewed Mikhail Allakhverdov, a Rhode Island man accused by the Tsarnaev family of radicalizing the older brother. 

Allakhverdov, known to the family only as "Misha," reportedly agreed to cooperate with investigators and has turned over his computer and cellphone to authorities, CNN reports. 

The elder Tsarnaev died after a shootout with federal agents and local police last Friday. His younger brother has been charged with using a weapon of mass destruction in the Boston attack. 

But federal law enforcement and intelligence officials have expanded their manhunt for additional suspects tied to the attacks in response to the older Tsarnaev's suspected ties to Islamic militants in Russia. 

Russian intelligence officials separately warned the FBI and CIA about the older Tsarnaev’s 2011 trip to southern Russia, where he may have reached out to militant Islamic groups in Dagestan.

Those warnings raised concerns the brothers could have been working as "lone wolf" operatives — individuals who have been influenced by but have no direct link to al Qaeda and other militant terror groups

Despite such concerns, House Intelligence Committee member Rep. Jan Schakowsky (D-Ill.) said there was still a lot of work to do before determining whether the Boston bombings were a true lone wolf attack. 

"I don't really agree that we're not any closer, because this is one of the most broad investigations that we've seen," Schakowsky said Sunday. "All of our law enforcement and intelligence community are doing a great job investigating and questioning all of the associations" in Dagestan and inside the United States.