Azamat Tazhayakov is accused of removing a backpack and other items from Tsarnaev's dorm room at the University of Massachusetts-Dartmouth several days after the bombings.
Prosecutors say Tazhayakov and another college friend, Dias Kadyrbayev, took the backpack containing fireworks out of Tsarnaev's room after they realised he was a suspect in the deadly attack. Twin bombs placed near the finish line of the 2013 marathon killed three people and injured more than 260. Tazhayakov has pleaded not guilty to obstruction of justice and conspiracy charges.