Sierra LaMar, who disappeared on the morning of March 16 as she made her way to school, may have been kidnapped, the Los Angeles Times reported Friday.
Sgt. Jose Cardoza of the Santa Clara County Sheriff's Department said the teenager may have been the victim of acquaintance abduction.
Little evidence has been uncovered in the investigation, Cardoza said. Police found Sierra's cellphone a day after her disappearance and her purse with clothing folded inside a day later.
Investigators have interviewed sex offenders in the area, including Sierra's father, who has been ruled out as a suspect in his daughter's disappearance.
Search teams Thursday found two used condoms next to a box marked "handcuffs" about a mile from where the girl is believed to have disappeared.
Investigators say it may just be a coincidence but they're sending the materials out for crime lab tests, just in case, the San Jose Mercury News reported.
"Other than the fact that it's pretty close to Sierra's mom's house, there's no indication at this time that it's related," Cardoza told the newspaper. "But we're collecting it as possible evidence."