An unidentified body was found Saturday near the home of a 13-year-old girl who disappeared around the time a registered sex offender unexpectedly visited her house, authorities said.

Hillsborough County Sheriff David Gee said he could not say whether the body was female but said it was partially submerged in an abandoned fish pond about a half mile from Sarah Michelle Lunde (search)'s home. It was found by a search dog.

"I cannot tell you any more about it than that right now," Gee said.

Gee said he let Sarah's mother, Kelly May Lunde, know of the discovery.

The sheriff has said David Onstott (search), a registered sex offender the mother once dated, has drawn investigators' attention but has not called him a suspect.

"We continue to investigate that lead. I will leave it at that," Gee said.

Sarah, who has a history of running away, was last seen on April 9, shortly after she returned home from a church trip. She was reported missing Monday, when her mother learned the teen wasn't at a friend's house.

About 200 volunteers joined detectives in the search Saturday, some hugging and crying as helicopters whirred overhead. Volunteers looking for the girl were sunburned from days spent combing through brush and swamp. One of Sarah's friends, Pamela Neely, 19, said she was still hopeful that the girl would be found alive.

"We're keeping our faith," she said. "Something good is going to happen. We believe it."

On Friday, detectives told the searchers to point out any bottles of Budweiser (search) or Bud Light. Sarah's brother said the sex offender, David Onstott (search), took a half-empty beer bottle during an unexpected predawn appearance at the family's home hours after the girl was last seen.

Onstott, 36, was being held without bond on separate charges. He was arrested Tuesday after he allegedly threatened another man with a screwdriver at a bar. He had spent 51/2 years in prison after being convicted in 1995 of sexual battery with physical force.

On Saturday, Gee said many beer bottles had been found and were being checked to determine if any DNA evidence is on them.

"What that may mean to this case later on, I don't know," he said.

The fathers of two previously slain girls have been involved in the search for Sarah: Mark Lunsford, whose 9-year-old daughter, Jessica, was found dead last month after disappearing from her Citrus County home, and Roy Brown, whose 7-year-old daughter, Amanda, was killed by a convicted child molester in 1997.

Roy Brown said he was worried for Sarah's mother.

"I just wanted the mom to know I'm here. Because things change, once the media and the searchers go, once it's all over, she still needs people," he said.