(WXYZ) - Law enforcement sources tell ABC News, Boston Marathon bombing suspect Dzhokhar Tsarnaev is awake and responding to questions. Authorities say Tsarnaev is reportedly sporadic in his written responses to questions.
Federal agents have started questioning him about possible accomplices or other explosive devices.
ABC News also learned Tsarnaev is only able to write because of wounds to his throat that may have been self-inflicted.
New information is surfacing about the dead brother, 26-year-old Tamalan. The FBI interviewed him two years ago after being tipped off by Russia about his possible terrorist ties.
US Representative Michael McCaul said "I gave them the benefit of the doubt but he was on the radar screen and somehow got off the radar screen and traveled overseas to one of the most dangerous parts of the world."
Later Monday, there will be a moment of silence in Boston marking one-week since the attack that killed three people and wounded more than 180 others.