Boston Marathon bombing suspect Dzhokhar Tsarnaev has pleaded not guilty to all charges in connection with the deadly twin explosions at the finish line of the April 15 race.
Tsarnaev entered the plea Wednesday in federal court in Boston, saying "not guilty" repeatedly as the 30 counts were read out at the arraignment.
The charges against him include using a weapon of mass destruction. If convicted, the 19-year-old Tsarnaev faces the death penalty or life imprisonment.
Wednesday's arraignment marked his first public appearance since his arrest several days after the bombings.
Three people were killed and more than 260 injured in the blasts. Tsarnaev also is accused in the killing of a policeman a few days after the bombings. At the time, he and his older brother, Tamerlan, were trying to flee authorities after security camera footage of them walking along the path of the Marathon before the explosions was broadcast nationwide.
Tamerlan Tsarnaev died in a shootout with police. Dzhokhar was arrested a day later while hiding in a boat in the backyard of a home in a Boston suburb. He was seriously wounded prior to his arrest.
The Tsarnaev brothers, both Muslims, spent much of the last decade living in the U.S.
They had roots in the volatile Russian regions of Chechnya and Dagestan, where Islamic extremists often attack Russian authorities. Law enforcement officials say Dzhokhar Tsarnaev wrote several messages on the inside of the boat, including one saying, "The U.S. government is killing our innocent civilians," and another saying, "We Muslims are one body, you hurt one, you hurt us all."
The courtroom Wednesday was packed with victims of the blasts and their families, as well as reporters and people who identified themselves as friends of Tsarnaev. Security was tight, with metal barricades set up.