WASHINGTON -- Accused Boston bomber Dzhokhar Tsarnaev has told FBI investigators that he and his brother were operating alone and did not receive assistance from outside terrorist groups, officials said Tuesday.

A team of federal agents peppered the 19-year-old with questions about the Boston Marathon bombing plot on Monday shortly before a federal magistrate read the charges against him and gave him the “Miranda warning” informing him of his constitutional right against self-incrimination.


Tsarnaev remains in a Boston hospital, where his condition on Tuesday was upgraded to fair.

Investigators separately have tentatively concluded that his older brother, Tamerlan Tsarnaev, 26, who died early Friday morning after a shootout with police, did not meet with Islamist militants during his six-month visit to Russia last year, according a senior U.S. counter-terrorism official.


Experts say the brothers increasingly appear to have been self-radicalized “lone wolf” operators who worked independently, using bomb recipes gathered from websites.

Terrorism expert Brian Jenkins of Rand Corp., who has studied every U.S. resident accused of plotting terror since 2001, says the Tsarnaevs fit a pattern of alienated young men who embraced Islamic extremism through the Internet.


But investigators continue to focus on Tamarlan’s 2012 trip to Dagestan and a Russian intelligence report that alleged contacts between Tamerlan and a suspected militant being tracked by Russian authorities.

The FBI had interviewed Tamerlan in 2011 at the request of Russian intelligence officials, who were concerned that he was an Islamic radical. It’s unclear what triggered their concern, but the FBI found no basis to investigate further, U.S. officials have said.

It appears that the FBI was not aware when Tamerlan left for Russia because his name had been misspelled on the passenger manifest provided by the Russian airline Aeroflot. Because the spelling did not match his records in a federal database, the FBI was not automatically alerted of his movements, a law enforcement official said.


However, Secretary of Homeland Security Janet Napolitano told a Senate panel Tuesday that the U.S. Customs and Border Protection database was alerted when Tamerlan boarded a flight to Russia.

“Even with the misspelling, under our current system, there are redundancies. And so the system did ping when he was leaving the United States,” Napolitano told the Senate Judiciary Committee. She did not say whether the FBI was informed of his movements at the time.


“By the time he returned [from Russia], all investigations had been -- the matter had been closed,” Napolitano said.

U.S. Customs and Border Protection collects names and biographical details of passengers entering and exiting the country. The computer database, called the Advance Passenger Information System, relies on air carriers to provide information because travelers are not required to submit to an exit screening when leaving the U.S.

A draft immigration bill written by eight senators would require federal officials to capture data directly from passports and travel documents whenever passengers leave the country through an airport or a seaport.

Napolitano said that provisions in the proposed bill would improve the accuracy of data coming into the system.


“The bill will help with this because it requires that passports be electronically readable as opposed to having to be manually input. It really does a good job of getting human error, to the extent it exists, out of the process,” Napolitano said.

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ken.dilanian@latimes.com


brian.bennett@latimes.com