In March 2011, the Russian government reached out to the FBI in the United States, with a belief that Tamerlan Tsarnaev, then 24-years-old, may have been involved with Islamic radicals.
The FBI interviewed Tamerlan in Boston and family members in Russia but concluded three months later that he was not a threat.
The Russian government then contacted the Central Intelligence Agency in September 2011 about Tamerlan, and his name was entered into its database under two different spellings, with two different dates of birth.
Tamerlan Tsarnaev left the United States in January 2012 for a six-month trip to the Dagestan region of Russia, and now the FBI is investigating whether he visited a bomb-making camp run by Dagestani militant, Abu Dujan.
It turns out Abu Dujan was killed in a shootout with Russian special forces in December 2012, four months before Tamerlan Tsarnaev was fatally gunned down in a shootout with Boston police and the FBI, as they closed in on him and his brother in the Marathon bombing case.
Tamerlan’s younger brother, 19-year-old Dzhokhar, was caught last Friday, hiding with gunshot wounds in a boat in the Boston neighborhood of Watertown.