Despite being told in 2011 that an F.B.I. review had found that a man who went on to become one of the suspects in the Boston Marathon bombings had no ties to extremists, the Russian government asked the Central Intelligence Agency six months later for whatever information it had on him, American officials said.
After its review, the C.I.A. also told the Russian intelligence service that it had no suspicious information on the man, Tamerlan Tsarnaev, who was killed in a shootout with the police early [on 19 April
2013]. It is not clear what prompted the Russians to make the request of the C.I.A.
The upshot of the American inquiries into Mr. Tsarnaev's
background was that even though he was found to have no connections to extremist groups, his name was entered into two different United States government watch lists in late 2011 that were designed to alert the authorities if he traveled overseas.
After the C.I.A. cleared him of any ties to violent extremism in October 2011, it asked the National Counterterrorism Center, the nation's main counterterrorism agency, to add his name to a watch list as a precaution, an American intelligence official said. Other agencies, including the State Department, the Homeland Security Department and the F.B.I., were alerted.
That database, the Terrorist Identities Datamart Environment, or TIDE, contains about 700,000 names. It is the main repository from which other government watch lists are drawn,
including the F.B.I.'s Terrorist Screening Database and the Transportation Security Administration's "no fly" list.
The information conveyed to the watch list included a transliteration from Cyrillic of Mr. Tsarnaev's
name — "Tamerlan Tsarnayev" — two dates of birth (both incorrect, officials said), and one possible variant spelling of his name.
[F.B.I.] agents concluded by June 2011 that they could not find any connections to extremists, and in August the results of the assessment were provided to the Russians, according to the United States official.
In closing out its report, the F.B.I.'s field office in Boston added Mr. Tsarnaev's
name to a second watch list, the Treasury Enforcement Communications System, or TECS, which was set up to send an electronic message to customs officials whenever Mr. Tsarnaev
left the country.
When Tamerlan Tsarnaev left the country on Jan. 12,
2012, for a six-month
trip to Dagestan and Chechnya, predominantly Muslim republics in the North Caucasus region of Russia, his flight reservation set off a security alert to customs authorities, the homeland security secretary, Janet Napolitano, told a Senate committee.
But Mr. Tsarnaev's departure apparently did not set off a similar alert on the TIDE watch list because the spelling variants of his name and the birth dates entered into the system — exactly how the Russian government had provided the data months earlier — were different enough from the correct information to prevent an alert, a United States official said.
When Mr. Tsarnaev returned in July, the travel alert "was more than a year old and had expired," Ms. Napolitano