Islamic militants in the northern Caucasus are denying involvement in the marathon attack. "The Caucasian Mujahedeen are not fighting with the United States of America," according to a Bloomberg translation of the statement, which came from unidentified rebel commanders in Dagestan. "We are at war with Russia, which is responsible not only for the occupation of the Caucasus, but also for heinous crimes against Muslims.”
The emerging trail of evidence suggests that Russian security forces did indeed warn the FBI about the elder of the two brothers accused in the bombing, Tamerlan Tsarnaev. A statement posted on the FBI website admits that "in early 2011, a foreign government asked the FBI for information about Mr. Tsarnaev. The request stated that it was based on information that he was a follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country’s region to join unspecified underground groups."