A police officer stands outside the John Joseph Moakley Courthouse in front of TV cameras after authorities arrested three men today in connection with the Boston Marathon bombings May 1, 2013 in Boston. (Darren McCollester/Getty Images)
BOSTON (USA Today) -- Three friends of Boston bombing suspect Dzhokhar Tsarnaev have been arrested on federal charges of conspiring to obstruct justice and making false statements for allegedly removing his backpack and laptop from his dorm room shortly after concluding he was involved in the attack.
None of the three is suspected of having advance knowledge of the plot or participating in the planning of the April 15 bombing, according to a law enforcement source.
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Dzhokhar Tsarnaev, 19, has already been charged in connection with the bombings that killed three people and injured more than 260 and is being held in a prison medical center
According to the federal complaint, the backpack that the friends discovered in his room at the University of Massachusetts Dartmouth contained fireworks from which explosive powder had been emptied.
Investigators say at least one of the bombs used in the April 15 Boston Marathon attack that killed 3 people and injured at least 260 was a pressure cooker packed with explosive powder and metal.
According to a federal complaint, two of the three -- Azamat Tazhayakov and Dias Kadyrbayev, both 19-year-old students from Kazakhstan -- are accused of obstruction of justice and conspiring to conceal the evidence found in Dzhokhar's dorm room.
A third man, Robel Phillipos, 19, of Cambridge, was charged with willfully making materially false statements to federal law enforcement officials during a terrorism investigation.
Lawyers representing the two Kazakh students in immigration court Wednesday morning on unrelated visa issues told the hearing that the pair had cooperated with Homeland Security and FBI investigators for hours and were only college friends of Tsarnaev and should be released, The Boston Globe reported.
The two have been held in a county jail for more than a week on allegations that they violated their student visas while attending the university with Tsarnaev, who is originally from Russia.
The federal complaint charges that the suspects went to Tsarnaev's dorm after concluding on April 18, two days after the bombing and the same day that his photo was circulated by police as a possible suspect, that he was indeed one of the bombers.
Kadyrbayev and Tazhayakov "have admitted that they agreed to get rid of it after concluding from news reports that Tsarnaev was one of the Boston marathon bombers," the affidavit says.
They then allegedly went to his dorm room, where they were let in by Dzkokhar's roommate, watched a movie and discovered his backpack containing the opened fireworks. They then removed the items and got rid of them, the complaint alleges.
Tsarnaev's 26-year-old brother Tamerlan, the other chief suspect in the bombings, died in a shootout with police three days after the attack. Dzhokhar was captured several hours later hiding in a boat in a backyard in Watertown, Mass.