Authorities in California are now saying missing teenager Sierra LaMar may have been abducted.
"The investigation process is leading more towards an involuntary missing person case. Under that umbrella is the theory that she is the victim of a kidnapping, abduction or voluntarily went missing and then at some point thereafter came into contact with someone and as a result is now being held against her will," Santa Clara Sheriff's Office Sgt. Jose Cardoza told The Huffington Post Thursday.
Cardoza said investigators base their suspicions on "hundreds of interviews that have been conducted, the very few items of evidence that we have in this case and the fact that no one saw her leave her house."
LaMar, 15, was last seen around 6 a.m. on March 16, when she left her Morgan Hill home to attend classes at Sobrato High School. The sophomore never made it to the bus or her school. LaMar's mother learned her daughter was missing when she got a message from the school's automated attendance system at 6 p.m., police said.
When LaMar's parents reported her missing to police, they said she did not have a history of running away from home.
On March 17, authorities found Lamar's cellphone discarded along a road roughly three-quarters of a mile northwest of her mother's home. According to police, the condition of the phone indicates it may have been tossed from a vehicle.
The following day, the sheriff's office found a purse and a backpack containing clothing belonging to LaMar in a location about two miles in the opposite direction from her bus stop -- and a mile from where investigators recovered her cell phone.
Forensic examinations of the items have not revealed any new leads. No other evidence has been found.
Sierra LaMar's parents are convinced their daughter is not a runaway.
"Please find it in your heart to release her," Marlene LaMar said last week on the "Today" show. "We love her so much. We ache for her and we are anxious to see her again."
She added a personal message to Sierra telling her to "be strong."
"I know you can survive this. You're a strong individual and you're going to make it back to us," Marlene LaMar said.
So far authorities have invested 3,000 hours in the case and have followed up on more than 500 tips. Investigators have also interviewed area sex offenders, including Sierra LaMar's own father, Steve LaMar, who was convicted in 2009 of one count of lewd or lascivious conduct with a child under 14, according to the Associated Press. The victim was not Sierra LaMar or her older sister. Police say Steve LaMar has been cooperative and is not considered a suspect in his daughter's disappearance.
"Now our focus is on people calling with information," Cardoza said. "We are asking people to report anything suspicious, specifically people acting suspicious -- all of a sudden changing their appearance or taking a high interest in the case."
Cardoza said it is too soon to tell if LaMar's disappearance is an isolated incident.
"We just don't know," he said. "There are a number of scenarios that may have taken place, [but] the person behind her disappearance is familiar with the Morgan Hill area."
The veteran law enforcement officer added, "We're all thinking positive and working hard on it."
Police have no suspects at this time and no persons of interest.
Sierra LaMar is 5-foot, 2-inches tall with a thin build. She has brown eyes and long black hair. Her clothing description at the time she went missing is unknown.
Anyone with information on this case is asked to contact Sheriff's Investigators at 408-808-4500 or the anonymous tip line at 408-808-4431. Email tips can be sent to firstname.lastname@example.org.
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Sierra LaMar, 15, vanished after leaving her Morgan Hills, Calif. home on March 16 and headed for school.
Police found LaMar's cellphone on Saturday, March 17 -- the day after she was last seen. Cops said they're searching her phone records for clues.
LaMar was a cheerleader in high school before moving to a new town, Morgan Hill, with her mother in October. Her parents are divorced and police said that both were cooperating with the investigation.
Police are treating LaMar's disappearance as a missing person case. Her parents insist it's unlikely that she ran away.
LaMar is 5-feet-2-inches tall with a thin frame. She was carrying a pink and black Juicy purse when she left home.
Anyone with information about LaMar may contact the Santa Clara County Sheriff's Office at (408) 299-2311
Deputy Peter Robinson, of the Santa Clara County Sheriff Underwater Search Unit, surveys a pond on Tuesday, April 17, 2012 in Morgan Hill, Calif. The search for missing 15-year-old Northern California girl expanded on Tuesday as investigators followed new leads one month since her disappearance. The Santa Clara County Sheriff's office would not say what the new leads were in the case of Sierra LaMar, except that they came from evidence already collected. The teen was seen leaving her Morgan Hill home on March 16. (AP Photo/Marcio Jose Sanchez)
A sign with a photo of missing teen Sierra LaMar is posted at an intersection on Tuesday, April 17, 2012 in Morgan Hill, Calif. The search for missing 15-year-old Northern California girl expanded on Tuesday as investigators followed new leads one month since her disappearance. The Santa Clara County Sheriff's office would not say what the new leads were in the case of Sierra LaMar, except that they came from evidence already collected. The teen was seen leaving her Morgan Hill home on March 16. (AP Photo/Marcio Jose Sanchez)
The Santa Clara County Sheriffs underwater search unit prepares to lower a zodiac into Calero Reservoir to look for clues in the disappearance of missing teenage girl Sierra LaMar Tuesday, March 27, 2012, in Morgan Hill, Calif. LaMar disappeared as she headed out for school on March 16, and her cellphone and bag were found tossed in two separate locations shortly after. (AP Photo/Ben Margot)
HOLD FOR STORY: In this photo from Monday, March 26, 2012, posters bearing images of missing teen Sierra LaMar are seen at Burnett Elementary School in Morgan Hill, Calif. LaMar disappeared as she headed out for school on March 16, and her cellphone and bag were found tossed in two separate locations shortly after. (AP Photo/Ben Margot)