\link{http://www.nytimes.com/2013/04/28/us/shot-at-boxing-title-denied-tamerlan-tsarnaev-reeled.html?pagewanted=2&_r=0&nl=todaysheadlines&emc=edit_th_20130428\lots of background stuff about Tamerlan from NY Times yesterday}
The wording of the Russians' warning the FBI/CIA about him in 2011 is really intriguing - I suppose they had been monitoring the communications of radical Islamists there & picked him up from that?
'In 2011, the Russian security service cautioned the F.B.I., and later the C.I.A., that ?since 2010? Mr. Tsarnaev had ?changed drastically,? becoming ?a follower of radical Islam.? The Russians said he was planning a trip to his homeland to connect with underground militant groups. An F.B.I. investigation turned up no ties to extremists, the bureau has said.'