According to a new inspector general’s report, Russia withheld information about the Boston bombing suspect Tamerlan Tsarnaev that would have led the F.B.I. to investigate more thoroughly into his background. The Russians withheld a phone call between Tsarnaev and his mother where they discussed Islamic jihad. The F.B.I. believed, based on the information given to them by Russia in 2011, that Tsarnaev posed a greater risk to Russia than he did to the United States.
The Russian government declined to provide the F.B.I. with information about one of the Boston Marathon bombing suspects that would most likely have led to more extensive scrutiny of him at least two years before the attack, according to an inspector general’s report.
Russian officials had told the F.B.I. in 2011 that the suspect, Tamerlan Tsarnaev, “was a follower of radical Islam and a strong believer” and that Mr. Tsarnaev “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.”
But after an initial investigation by the F.B.I., the Russians declined several requests for additional information about Mr. Tsarnaev, according to the report, a review of how intelligence and law enforcement agencies could have thwarted the bombing.
At the time, American law enforcement officials believed that Mr. Tsarnaev posed a far greater threat to Russia.
The new inspector general’s report found that it was only after the bombing occurred last April that the Russians shared with the F.B.I. the additional intelligence, including information from a telephone conversation the Russian authorities had intercepted between Mr. Tsarnaev and his mother in which they discussed Islamic jihad.