Azamat Tazhayakov is charged with obstruction of justice and conspiracy.
Prosecutors ended their case Monday after the testimony of an FBI agent. The defense called no witnesses. Closing arguments in his trial are scheduled for Wednesday.
The Kazakhstan-born Tazhayakov is accused along with another friend of removing a backpack containing altered fireworks from Tsarnaev's dormitory room several days after the 2013 bombings. Twin bombs placed near the finish line of the marathon killed three people.
The defense maintains that the other friend removed the backpack and fireworks and later threw the items away. Prosecutors say both men shared in the decision to get rid of the items.