As the [FBI] was accused of "dropping the ball" over the case, NBC News reported that Tamerlan Tsarnaev had been seen making six visits to a known Islamic militant [Gadzhimurad Dolgatov, who was killed by Russian police last December in Makhachkala] in a mosque in the Russian republic of Dagestan.
The visits came during a six month trip that Tamerlan made to the city of Makhachkala to see his family, NBC said.
According to a local police official, a case file on Tsarnaev was then handed over to the FBI along with a request for further information. However, the FBI never replied.
Michael McCaul, the chair of the House Homeland Security Committee, said the FBI must explain why it failed to keep track of Tsarnaev after the 2011 interview, particularly after he visited his family in Dagestan, which is a known centre of Islamist militancy and training facilities.
"If he [Tamerlan Tsarnaev] was on the radar and they let him go, if he was on the Russians' radar, why wasn't a flag put on him, some sort of customs flag?" Mr McCaul asked
on CNN, adding that there were clear signs that Tsarnaev had been radicalized during his trip.
In a further sign that Tsarnaev's record was in the US security apparatus, the New York Times reported yesterday that a "hold" had been placed on his citizenship request by the Department of Homeland Security after routine background checks discovered the FBI's former interest in him.