Dzhokhar Tsarnaev’s arraignment was scheduled for Wednesday afternoon in federal court in Boston. He has been charged with using a weapon of mass destruction in the bombings that killed three people and wounded more than 260.

The courthouse is expected to be jammed for 19-year-old Tsarnaev’s appearance. A spokeswoman for the U.S. attorney’s office said space is being reserved in the main courtroom for victims’ families, but she wouldn’t indicate how many planned to attend. Court officials have set aside an overflow courtroom to broadcast the hearing for the media.

Reporters and spectators began lining up for seats in the courtroom at 7:30 a.m. as a dozen Federal Protective Service officers and bomb-sniffing dogs surrounded the courthouse.

Four hours before the hearing, Tsarnaev arrived at the courthouse in a four-vehicle motorcade that included a van, a Humvee and a state police car.

A group of about a dozen Tsarnaev supporters cheered as the motorcade arrived. The demonstrators yelled “Justice for Jahar,” as Tsarnaev is known. One woman held a sign that said, “Free Jahar.”

Lacey Buckley, 23, said she traveled from her home in Wenatchee, Wash., to attend the arraignment. Buckley said she has never met Tsarnaev but came because she believes he’s innocent. “I just think so many of his rights were violated. They almost murdered an unarmed kid in a boat,” she said.

Brittney Gillis, a student at the University of Massachusetts-Dartmouth, where Tsarnaev attended, came to the courthouse because she wanted to see the suspect. She said he used to walk her friend home in the evenings because he was worried about her being alone.

“He would walk her from the campus library to her dorm at night,” she said.

Tsarnaev has yet to appear publicly since his April 19 arrest. His initial court appearance took place at a hospital, where he was recovering from injuries suffered in a shootout with police the day before in the Boston suburb of Watertown.

Authorities say he had escaped in a hijacked car after running over his brother and alleged co-conspirator, Tamerlan Tsarnaev, who died following the shootout with police. But he was found the next day after a lockdown in Watertown was lifted and a local homeowner noticed blood on the dry-docked boat.

Tsarnaev’s arrest stunned those who knew him as a likable high school athlete in Cambridge, where he lived with his older brother after his parents left for Russia.

His parents were in Makhachkala, in the southern Russian province of Dagestan, on Wednesday. His mother declined to comment.

Prosecutors say Tsarnaev, a Muslim, wrote about his motivations for the bombing on the inside walls and beams of the boat where he was hiding.

He wrote the U.S. government was “killing our innocent civilians.”

“I don’t like killing innocent people,” he said, but also wrote: “I can’t stand to see such evil go unpunished. … We Muslims are one body, you hurt one you hurt us all.”

The indictment also said that, sometime before the bombings, Tsarnaev downloaded Internet material from Islamic extremists that advocated violence against the perceived enemies of Islam.

Three people — Martin Richard, 8; Krystle Marie Campbell, 29; and Lingzi Lu, 23 — were killed by the bombs, which were improvised from pressure cookers. Authorities say the Tsarnaevs also killed Massachusetts Institute of Technology officer Sean Collier days later while they were on the run.

Numerous bombing victims had legs amputated after the two explosions, which detonated along the final stretch of the race a couple hours after the elite runners had finished.