A body believed to be that of a missing 17-year-old California girl was found Tuesday afternoon, San Diego Sheriff William Gore said.

Gore said the body was found in a shallow grave covered in debris after a searcher noticed something that looked suspicious.

The teen, Chelsea King, disappeared Thursday from a wooded park in San Diego County. The body was found in a wooded area near a tributary that leads down to a lake, Gore said.

"A positive ID has not been made, but there is a strong likelihood that we have found Chelsea's," Gore at an afternoon news conference. "They [her parents] are devastated ...

"This was our worst fear, that we would find her as we did today," Gore said.

King is a straight-A student at Poway High School who plays French horn for the San Diego Youth Symphony, competes on her school cross-country team and volunteers in a peer counseling program.

A sex offender suspected in the disappearance of King was arrested Sunday. John Albert Gardner III served only five years in prison for molesting a girl a decade ago after prosecutors rejected a psychiatrist's advice to seek a stiffer punishment, court documents state.

Prosecutors said in 2000 that Gardner's lack of significant prior criminal record justified less than the maximum sentence for molesting a 13-year-old girl.

Gore declined to say how finding the body would affect Gardner or any charges he could face, adding police would present the facts to the district attorney. Gore also wouldn't comment on any possible evidence that was found.

LIVESHOTS: The Search for Chelsea King

The San Diego Union-Tribune said Tuesday that Gardner had faced a maximum of nearly 11 years in prison under terms of his plea agreement. Prosecutors urged six years — the sentence later ordered by a judge.

In their 11-page sentencing memo, prosecutors said Gardner "never expressed one scintilla of remorse for his attack upon the victim" despite overwhelming evidence.

The girl was beaten before escaping from his home and running to a neighbor.

Psychiatrist Dr. Matthew Carroll wrote in sentencing documents, "There is no known treatment for an individual that sexually assaults girls and does not admit to it in any way."

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FoxNews.com's Michelle Maskaly and The Associated Press contributed to this report.