Dzhokhar Tsarnaev was injured during the police manhunt and remains in hospital in a fair condition.
The hearing on Capitol Hill comes less than three weeks after Dzhokhar Tsarnaev's arrest.
Three of Dzhokhar Tsarnaev's friends have been accused of covering for the bombing suspects.
The FBI is examining Dzhokhar Tsarnaev's laptop, two federal law enforcement officials told CNN.
Kadyrbayev texts Dzhokhar Tsarnaev to tell him he looks like one of the bombing suspects.
Kadyrbayev and Tazhayakov were with Dzhokhar Tsarnaev at a weekly study circle in January.
Dzhokhar Tsarnaev had left an hour earlier, a roommate told them, according to the affidavit.
The following day Mr. Tazhayakov got a ride home from school from Dzhokhar Tsarnaev.
Dzhokhar Tsarnaev attended the University of Massachusetts Dartmouth with the three friends charged Wednesday.
Holder also responded to criticism that the surviving suspect, Dzhokhar Tsarnaev, was read his Miranda rights.
His younger brother, Dzhokhar Tsarnaev, 19, was captured and charged in connection with the attack.
BBC: Boston bombing suspects' mother regrets emigration to US
Dzhokhar Tsarnaev was in New York in late 2012, likely in November, Kelly said.
CNN: Father of Boston bomb suspects to fly from Russia to U.S.
Surveillance tape late Thursday showed Dzhokhar Tsarnaev, Suspect No. 2, at a gas station.
Several sources identified the other brother, who remained on the lam, as Dzhokhar Tsarnaev, 19.
Tsarnaev's brother, Dzhokhar Tsarnaev, 19, is being held in a prison hospital after being shot before capture.
Todashev, 27, knew Dzhokhar Tsarnaev, also a suspect in the April 15 bombings, the official said.
Tamerlan Tsarnaev died April 19 after a firefight with police, and Dzhokhar Tsarnaev, who survived, has been charged.
WSJ: Man Connected to Boston Bombing Suspects Killed in Standoff
Dzhokhar Tsarnaev, 19, was listed in fair condition as he recovered from wounds suffered during a getaway attempt.
Dzhokhar Tsarnaev, 19, is hospitalized with gunshot wounds, including one to the throat that has hampered his speech.
That official would not comment on any motive or specifics on what Dzhokhar Tsarnaev has communicated to officials.
The Obama administration said it had no choice but to prosecute Dzhokhar Tsarnaev in the federal court system.
All day: Hundreds of law enforcement officers go door-to-door on 20 streets in Watertown, looking for Dzhokhar Tsarnaev.
Many of those who knew Dzhokhar Tsarnaev in Cambridge expressed disbelief at his alleged involvement in the bombings.
Todashev, 27, knew Dzhokhar Tsarnaev, who also is a suspect in the April 15 bombings, the official said.
Authorities believe brothers Tamerlan and Dzhokhar Tsarnaev are responsible for the bombing attack.
WSJ: Last Boston Marathon Bombing Patient, Erika Brannock, Released From Hospital
The FBI has a laptop belonging to Dzhokhar Tsarnaev, Tamerlan's younger brother, two federal law enforcement officials told CNN.
Three classmates of Dzhokhar Tsarnaev are accused of lying to investigators and conspiring to destroy evidence in the bombing.
Dzhokhar Tsarnaev is being treated for gunshot wounds at a federal Bureau of Prisons medical center in Devens, Massachusetts.
The FBI affidavit also detailed contacts between Dzhokhar Tsarnaev and the three friends in the days after the bombings.
Dzhokhar Tsarnaev, injured and captured after a manhunt, is being held by authorities.
应用推荐