POWAY, Calif. - Thousands of teachers, classmates and neighbors filled a high school football stadium Saturday to honor a 17-year-old girl whose body was discovered in a shallow, lakeside grave, allegedly killed by a registered sex offender.

Family and friends told the crowd of Chelsea King's big dreams, terrific sense of humor, sense of style, athleticism and thirst for knowledge and adventure.

They were profusely thankful for the massive search for her after she went missing Feb. 25 on a run at a San Diego Park and for the outpouring of sympathy after her body was found five days later.

"On Feb. 25 our lives changed dramatically and will remain changed forever," said Chuck McCully, her uncle. "Our hearts were shattered."

Speakers also said her heinous death has galvanized people to prevent other children from falling victim to predators. A moment of silence was held for Amber Dubois, whose bones were found last week north of San Diego more than a year after she went missing while walking to school.

"Chelsea was a force who was setting out to change the world," said Cindy Provenzano, a family friend. "She did not die in vain and neither did Amber Dubois."

John Gardner, 30, has pleaded not guilty to Chelsea's murder and attempted rape of another woman in December. He is also a suspect but has not been charged in the killing of Amber Dubois.

Gardner served five years of a six-year sentence for molesting a 13-year-old neighbor in 2000. He was on parole for three years, until September 2008.

"Sometimes we just get sick and tired of the brokenness in this world," Harry Kuehl, pastor of the Church of Rancho Bernardo, said during Saturday's ceremony.

Chelsea was a straight-A student at Poway High School, ran on the cross-country team, played French horn in the San Diego Youth Symphony and was active in her school's peer counseling program. She was a tireless volunteer in school and community activities, whether working at a prom for special education students or packaging food for needy families in Africa.