San Francisco 49ers quarterback Alex Smith has reportedly joined the search for a missing California girl who disappeared more than two weeks ago on her way to school.

Smith was among 581 volunteers who turned out Saturday to search for 15-year-old Sierra LaMar, of Morgan Hill, Calif., who was last seen March 16, the Contra Costa Times reported.

"He wasn't there for attention. He was there to search," Marc Klaas, founder of the KlaasKids Foundation, told the newspaper. "It was about his heart. It's certainly a touching thing, and it's a huge thing, too. By showing up, he provided a value that went well beyond his own presence as a searcher."

Last week, searchers found possible items of interest in the case, including condoms and an empty box labeled "handcuffs" not far from where she was last seen.

Santa Clara sheriff deputies confirmed that a volunteer searching for LaMar discovered the items near a dead-end road about 2 miles from the girl's home, Fox affiliate KTVU-TV reported.

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The potential evidence, part of a series of items discovered by volunteers, will be sent to the county crime lab for testing, authorities said.

But authorities noted that the items were found in an area known to authorities as a place where underage people go to drink alcohol and party.

Investigators said last week that they think LaMar, a sophomore at Sobrato High School, likely was the victim of an acquaintance abduction.

She last was seen March 16 leaving her home at around 7:15 a.m. to walk to a school bus stop. Police dogs searching for the girl lost her scent on the driveway of her home.

The teenager usually walked from her home to a nearby bus stop, but a bus driver said he saw no sign of her.

LaMar's phone was recovered shortly after her disappearance about three-quarters of a mile from her home after police tracked its electronic ping. Police said the last text LaMar sent out was shortly before 7 a.m. the day she disappeared, and it was not a distress text. He also said there was no forensic evidence on the phone.

The girl's bag also was discovered a couple of miles from her home. Her pants and shirt were found neatly folded inside the Juicy brand bag, though it's not known whether those are the clothes she was last seen wearing, police said.

There is currently no person of interest in the case, and police are still treating it as a missing person case.

Police said they have interviewed registered sex offenders in the area near where LaMar was last seen. There are 276 registered sex offenders in the area, according to the station.

Sierra lives with her mother and stepfather. She transferred to the school in October after the family moved from Fremont to Morgan Hill. She is described as having a very good relationship with her family.

The girl's father, Steve LaMar, who lives some 40 miles away in Fremont, is a registered sex crimes offender but is not considered a suspect in the case.

Sierra LaMar is described as 5 feet, 2 inches tall, with brown hair. She was last seen carrying a Juicy brand pink and black purse.

Anyone with information on the teenager's whereabouts is being urged to call the Santa Clara County Sheriff's Department at 408-299-2311.