John Albert Gardner, a convicted sex offender, pleaded not guilty to the rape and murder of Chelsea King, 17.
King disappeared last week while going for a run at a community park. The teenager grew up in west suburban Naperville before moving to California with her family.
Thirty-year-old Gardner was taken into custody on Sunday. A body believed to be King was recovered in a shallow grave by police on Tuesday. Authorities are working to confirm that identity.
During Wednesday's court appearance, Gardener -- dressed in blue jail clothes -- stared at the floor as the charges were read against him. He faces one count of first degree murder and one count of assault with intent to commit rape. He pleaded not guilty.
"We want to make sure that justice is done for Chelsea... and we want to make sure that we do everything we can to preserve the case and to make sure that the person responsible is held accountable," said Bonnie Dumanis, San Diego County Dist. Attorney.
King's friends in Naperville hope the arrest and discovery of the body will bring some closure to her family.
"We don't understand why it happened, it's shocking," said Kara Weiss, Waubonsie High School.
King spent most of her freshman year at Waubonsie Valley before moving to suburban San Diego with her friends. She spent 10 years in Naperville and those who knew her say this is almost surreal.
"And when I heard that couldn't believe it because you see stuff like that on CSI, but never think someone you actually know...this girl is going to die in a horrible way it's so sad," said Ellie McHale, Waubonsie High senior.
Hundreds of people searched for King after she disappeared near Lake Hodges. On Tuesday night, thousands joined her family for a candlelight vigil.
Police say the suspect once lived at his mother's house, which is located near the park where King disappeared. Someone spray-painted a message on the garage: "Chelsea's blood is on you. Move out."
Police say Gardner molested a 13-year-old neighbor when he lived here in 2000.
"We want him out of here. We want this to stop. We want to figure out how we can prevent it from happening to any of the innocent girls and families from happening again," said a neighbor.
Chelsea's former classmates and teachers at Waubonsie High are saddened by not one but two tragedies. A senior was killed in a car crash recently. For some, this is almost too much to bear.
"I caught wind of it yesterday and one of my students in class was having a hard time with it, struggling with it," said Nate Gehrt, English teacher.