03/23/2012 01:18 pm ET Updated May 11, 2012

Sierra LaMar's Parents Believe She Was Abducted, Not A Runaway (VIDEO)

Sierra LaMar's parents believe that their teenage daughter, who has been missing since March 16, was abducted and did not run away.

Investigators have not found any specific evidence signaling foul play, but Marline and Steve LaMar are asking anyone who may be involved with her disappearance to return their daughter.

"Please find it in your heart to release her," Marlene LaMar said on the "Today" show. “We love her so much. We ache for her and we are anxious to see her again."

She added this personal message to Sierra, a 15-year-old sophomore at Sobrato High School in Morgan Hill, Calif.: "Sierra, if you’re out there, please be strong. I know you can survive this. You’re a strong individual, and you’re going to make it back to us."

On Sunday, the Santa Clara County 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 undamaged cell phone on Saturday.

However, the cell phone and clothes have not provided any clues, according to investigators.

Still, her parents don’t believe that the packed bag of clothing, which, according to CBS San Francisco, included a neatly folded pair of pants and a San Jose Sharks t-shirt, indicates she was trying to run away.

"I haven't thought of that, but I know that frequently she would borrow clothes from her friends," Marline told "Today." "She would bring things to her friends to wear and borrow things that she really liked that they were wearing. She's done that in the past quite a few times."

Steve LaMar added he can't think of a reason why his daughter might pack a bag of clothes. "It's baffling," he said.

As part of the investigation, FBI officials set up a roadblock this morning near the spot where she was last seen and are stopping every driver and quizzing them about their recollection of the March 16 morning when Sierra disappeared, NBC Bay Area reported.

"What we know is Sierra probably didn't leave the (street)," Santa Clara County Sheriff Laurie Smith said. "No one sees her that morning. We wanted to rule out that any of the people here [on LaMar's street] had anything to do with her disappearance."

Meanwhile, authorities say that while they have been interviewing sex offenders in the area, Sierra's father is not a suspect despite being convicted of one count of committing a lewd or lascivious act with a child under 14. He was sentenced to a year in jail, which he served in 2009.

He told the "Today" show, 'The only thing I'm going to say, as I stated, I want the focus to be on Sierra and (we've) got to find Sierra. I'm not a suspect or person of interest, so I just want that removed. We've been cooperating with authorities, and they've stated that also. I want that out of the way so that we can focus on finding Sierra."




Sierra LaMar