Dzhokhar Tsarnaev, accused of killing three Boston Marathon spectators and injuring 260 others in the first deadly terrorist bombing in the U.S. since Sept. 11, 2001, pleaded not guilty to murder charges Wednesday, July 10, Bloomberg reports.

He has been charged with using a weapon of mass destruction in the April 15 blasts that killed three people, including an eight-year-old boy.

The accused could face the death penalty if convicted over what was the worst mass-casualty attack on U.S. soil since September 11, 2001.

Tsarnaev was not in court last month during an indictment hearing, when a federal grand jury agreed that he should be tried on 30 charges. His first court appearance took place at his hospital bedside, where he was recovering from injuries received in a shoot-out with police during the manhunt for the bombers. He was later transferred to a prison hospital near Boston.

The defendant's brother and alleged co-conspirator, 26-year-old Tamerlan Tsarnaev, was killed in that gun battle.

Authorities say the accused ran over his older brother as he fled the shoot-out in a hijacked car. Dzhokhar Tsarnaev was found the next day, April 19, hiding in a boat in a residential garden in Watertown, Massachusetts.

According to the indictment, he wrote about his motivations for the bombing on the inside walls and beams of the boat.

Dzhokhar Tsarnaev is also charged with the death of a policeman he and his brother allegedly shot dead as they fled the authorities, and for a carjacking days after the attacks.

The indictment said that he had downloaded internet material from Islamist radicals sometime before the blasts.

According to the charge sheet, the brothers made bombs from pressure cookers, low-explosive powder, ball bearings, nails, adhesive, electronic components and other material.

Dzhokhar Tsarnaev is accused of aiding and abetting his brother by planting and detonating one of the two bombs near the finish line.