This piece in today's New York Times is excellent: "Boy at Home in U.S., Swayed by One Who Wasn’t."

I recommend another piece today in the Times, too. "Suspects With Foot in 2 Worlds, Perhaps Echoing Plots of Past," talks about immigrants caught between American life and Islamic loyalty:

Mr. Fishman cautioned that it was too early to draw any firm conclusions about the Tsarnaev brothers, but said there were intriguing echoes of other cases in which young men caught between life in America and loyalty to fellow Muslims in a distant homeland turned to violence, partly as a way of settling the puzzle of their identity.

Akbar Ahmed, the chairman of Islamic studies at American University in Washington, described such men: “They are American, but not quite American.” His new book, “The Thistle and the Drone: How America’s War on Terrorism Became a War on Tribal Islam,” examines how tribal codes of hospitality, courage and revenge have shaped the reaction to American counterterrorism strikes.

“They don’t really know the old country,” Professor Ahmed said of young immigrants attracted to jihad, “but they don’t fit in to the new country.”

Add feelings of guilt that they are enjoying a comfortable life in America while their putative brothers and sisters suffer in a distant land and an element of personal estrangement — say, Tamerlan Tsarnaev’s statement in an interview long before the attack that after five years in the United States, “I don’t have a single American friend” — and it is a combustible mix.

“They are furious,” Mr. Ahmed said. “They’re out to cause pain.”

Read them both if you have the time.