BOSTON (CNN) — The suspects involved in the Boston Marathon bombing were brothers from the Russian Caucasus who moved to Kazakhstan before coming to the United States several years ago, a source briefed on the investigation told CNN.
One of the brothers, identified by several sources as Tamerlan Tsarnaev, 26, had studied engineering at Bunker Hill Community College but had taken off a year to train as a boxer, the source said.
The source said that a posting on a social media site under his name included the comments: "I don't have a single American friend. I don't understand them."
He was wounded overnight and taken to a hospital, where he died.
Several sources identified his brother, who remains on the lam, as Dzhokhar Tsarnaev, 19.
The source added that it should not be assumed that the brothers were radicalized because of their Chechen origins.