He found her 1994 BMW parked at a San Diego park late Thursday.
The parents say Chelsea is a straight-A student who ran cross-county and is active in her school's peer counseling program.
John Gardner III, a registered sex offender, has been booked for investigation of murder and remains in custody without bail after his arrest Sunday in San Diego.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
SAN DIEGO (AP) " A registered sex offender arrested for investigation of murdering a missing 17-year-old San Diego County girl is refusing to cooperate with authorities who renewed their search Monday at the park where she vanished Thursday.
John Gardner III, 30, remained in custody without bail after his arrest Sunday for investigation of murder and rape. It was not immediately clear whether he had hired an attorney.
No criminal charges had been filed, but district attorney's spokesman Steve Walker said a decision would be made by Wednesday.
Chelsea King of Poway disappeared after going for a run near Lake Hodges at Rancho Bernardo Community Park in San Diego, a popular regional park full of trails. Her BMW, with her cell phone and iPod inside, were found later that night.
Some 1,500 law enforcement personnel, dogs and volunteers failed to find the teen on Sunday.
Investigators searched a townhouse Monday about a mile from the park where neighbors say Gardner's mother and stepfather lived, the San Diego Union-Tribune reported.
Sheriff's spokeswoman Susan Plese said she could not confirm that report.
Sheriff William Gore, appearing with the girl's parents on ABC's "Good Morning America," said Gardner was arrested after investigators discovered a piece of physical evidence linking him to the case. He did not elaborate.
Gardner, who gave his residence as Lake Elsinore, about 75 miles north of the park, was arrested at a restaurant in Escondido.
His interrogation had not been productive, Gore said.
"We questioned Mr. Gardner into the evening and so far we still don't know where Chelsea is," Gore said. "We're confident that we have the right man in custody. Now we've just got to find Chelsea."
Investigators also suspect Gardner could be tied to a Dec. 27 assault on a female jogger in the same park, Gore said.
He was required to register as a sex offender because of a conviction for lewd or lascivious acts with a child under 14, the Megan's Law Web site said.
The search for King, a straight-A senior at Poway High School, also took to the Internet, where a Web site was created at findchelsea.com.
At the high school Monday, students and staff wore blue shirts to represent the color of the teen's eyes and tied blue ribbons around campus light poles.
Principal Scott Fisher thanked students for their search efforts and cautioned them about spreading rumors by cell phone and Internet.Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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