Boston, July 11 (IANS): In his first court appearance, Boston Marathon bomb suspect Dzhokhar Tsarnaev has pleaded not guilty to charges of killing four people and wounding more than 200, as blast victims looked on.

Tsarnaev, 19, faces 30 counts of using a weapon of mass destruction in the two 15 April blasts that killed three, including an eight-year-old boy. Prosecutors could press for the death penalty for 17 counts, CNN reported.

The suspect has also been charged over the death of a Massachusetts Institute of Technology (MIT) police officer, who was allegedly shot dead by Tsarnaev and his brother Tamerlan three days after the attack.

He is also charged in a carjacking incident and with downloading internet material from Islamist radicals some time before the blasts.

Tsarnaev was dressed in an orange jail jumpsuit, his hair long and shaggy, his left arm in a cast, the news channel said. He was wounded in the pursuit-during which his brother, Tamerlan, was killed-and he appeared to have an injury to the left side of his face.

MIT police lined up outside the courthouse as the hearing neared its end Wednesday afternoon in a show of solidarity with their fallen comrade, Sean Collier.

Inside, about 30 survivors of the attack watched as Tsarnaev appeared before US Magistrate Judge Marianne Bowler.

Tsarnaev looked back at the spectators in the packed courtroom before entering his plea-and to Liz Norden, whose two sons each had a leg amputated after the attacks, he appeared to smirk.

Prosecutors said Wednesday they expect to call between 80 and 100 witnesses in a three- to four-month trial.

The indictment details the planning that allegedly went into the attacks.

Tamerlan Tsarnaev bought 48 mortars, it says.

It also says that Dzhokhar Tsarnaev downloaded a copy of Inspire magazine, which included instructions on building IEDs using pressure cookers and explosive powder from fireworks.

Pressure cooker bombs were used in the Boston Marathon attacks.