A phone message left for a spokeswoman for the U.S. Attorney's Office was not immediately returned Tuesday night. A message left for Dzhokhar Tsarnaev's federal public defender was also not immediately returned.
Authorities allege that Dzhokhar Tsarnaev, 20, and 26-year-old Tamerlan Tsarnaev, ethnic Chechens from Russia, planned and carried out the twin bombings near the finish of the marathon on April 15. Three people were killed and more than 260 were injured.
Dzhokhar Tsarnaev faces 30 federal charges, including using a weapon of mass destruction and 16 other charges that carry the possibility of the death penalty.
Tamerlan Tsarnaev died in a gunbattle with police as authorities closed in on the brothers several days after the bombings.
