And the new criminal complaint against them also may shed new light on Mr. Tsarnaev’s interest in bombmaking. Previous news accounts have widely portrayed his older brother as the mastermind of the attacks, but the complaint says that two of the friends heard the younger Tsarnaev say, a month before the attacks, that he knew how to make bombs.
The document also quotes one of the friends saying that Tsarnaev appeared to have cut his hair short when the two saw each other on the campus the University of Massachusetts at Dartmouth on April 17, two days after the bombing. The timing of that apparent effort at a changed appearance is significant; the next day the FBI made photos of the bombing suspects public.
The criminal charges made public Wednesday do not allege that any of the three newly arrested men were involved in the bombings or knew about any plans. But these men could potentially face years in prison for obstructing justice.
Mr. Kadyrbayev and Mr. Tazhayakov, who are Kazakhstan nationals studying in the US, have been held in jail for more than a week on allegations that they violated their student visas. Now they are charged with conspiring to destroy, conceal, and cover up tangible objects belonging to the suspected bomber. That could carry a sentence of up to five years in prison and $250,000 fine.