Authorities searching for a Brigham Young University student swarmed the banks of the Provo River on Thursday night after two people surrendered a bicycle that likely belonged to the 22-year-old woman.

It was a significant development in the disappearance of Camille Cleverley, who has been missing since Aug. 30.

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A dam upstream at Deer Creek Reservoir was closed to lower the depth of the river and check for any evidence of the BYU senior, Provo police Lt. John Guyerman said.

"We don't know if she's here. All we have to go on is a bicycle," he said.

The bike was turned in by two people who snatched it Saturday after finding it unattended on a path near Bridal Veil Falls, Guyerman said. They came forward after hearing about the missing woman.

Cleverley was last seen riding a week ago, about 40 miles south of Salt Lake City. Police were working to confirm that the Schwinn bike was hers.

Cars and pedestrians were turned away from the falls, a popular recreation spot, while officers delivered all-terrain vehicles, canoes and boats to the river Thursday night.

Earlier in the day, Provo police held their first news conference, making a public plea for information about Cleverley and the bicycle.

"We have a daughter, a sister, a friend that is missing," Police Chief Craig Geslison said, choking up. "We have a community that cares. We want to find her."

Hundreds of volunteers, including BYU students and faculty, have been combing Provo Canyon and other rugged areas where Cleverley liked to ride. The new school year began Tuesday.

"You're really in the thick of it up there," Jennene Allen of Lindon told the Daily Herald of Provo while searching with her husband.

Officers inspected a car wash Wednesday night but said it did not produce clues about her whereabouts.

If Cleverley was abducted, brother David Cleverley publicly urged the perpetrator to release her — "if he has sensitivity and humanity."

Before the new school year, the Boise, Idaho, native spent the summer living with the family of her boyfriend, David Sperry, father Dick Sperry said.

"They put him through the mill. They really worked him over," Dick Sperry told The Associated Press, referring to tough questioning during his son's numerous interviews with police.

"But that's their duty. They would do that with any boyfriend," the father said. "But I'm satisfied, knowing the timeline, that he had nothing to do with it. ... He loves this girl."

David Sperry was involved in the search Thursday and unavailable for comment.

Police Capt. Cliff Argyle, who is leading the investigation, said the boyfriend was given a "voice-stress analysis" test and has been cooperative. He declined to discuss the results but said the test is a reliable indication of someone's honesty.

Argyle said no one has been identified as a suspect but "everyone is interesting to us if they had any contact with Camille."

He said eight FBI agents were assisting and police in Boise were watching the Cleverley family's home in case she turns up there. Her parents and other family members have been in Provo participating in the search.

Cleverley's debit card was used Aug. 31, a day after she was last seen, to buy doughnuts and energy drinks at a local store. The store had no surveillance cameras, and police said they didn't know if she or someone else made the purchase.

Cleverley is a blue-eyed blonde, 5 feet 5 inches tall and 110 pounds.