An interesting side note to this mess...
Some news sources are saying:
"As the five-day manhunt for the suspects drew to a close, the FBI also confirmed that its agents in Boston had interviewed TamerlanTsarnaev in 2011 at the request of a foreign government. A law enforcment official said the request came from the Russian government, concerned about Tsarnaev’s potential ties to Chechen terrorists. But after that interview, the FBI did not follow him further, officials said."
The Chechens and Russia, and Putin of course, are now worried about perceived connections.