The 19-year-old accused in the April 15 Boston Marathon bombing has pleaded not guilty to all 30 criminal charges against him, which included the use of a weapon of mass destruction to kill.
Ethnic Chechen Dzhokhar Tsarnaev entered the plea at his arraignment at a federal courthouse in Boston on July 10.
Reports from inside the courtroom said the naturalized American citizen spoke into a microphone to plead "not guilty" several times in a Russian accent.
The bombings killed three people and wounded more than 260. Prosecutors are weighing whether to ask for the death penalty.
Tsarnaev's alleged co-conspirator and brother Tamerlan was killed during a gunbattle as police closed in.
Several seats in the courtroom were reserved for victims of the bombing and their families.
Many of the victims who attended the proceedings were emotional.
Mildred Valverde was wounded while standing at the finish line of the marathon at the time of the blasts.
"Just his presence being there after all the destruction he caused and all the hurt he caused everyone, just to be in the same room with him was bothersome. I'm heading home now," Valverde said.
Liz Norden's two sons each lost a leg during the bombing.
"I don't know. I actually felt sick to my stomach. It's very emotional for me. I actually felt -- I'm angry, but I actually feel... I don't know. I feel sorry for everybody. I was upset when the sister cried because it just made me want to... I don' t know...," Norden said.
Security was tighter than normal outside Boston's U.S. District Courthouse.
Prosecutors said the government planned to call between 80 and 100 witnesses and that the trial would likely last three to four months.
Based on reporting by AP and Reuters