Earlier Tuesday morning, Marlene LaMar talked through tears to drivers coming through the intersection where she believes her daughter was last seen. She handed out fliers and fished for information, perhaps finding a nugget of information that might help find her daughter. Sierra has not been seen since Friday morning when she left her house in unincorporated Morgan Hill for the school bus stop at the intersection. She never boarded the bus.
"They might have seen something out of the ordinary and I was just trying to tell them to kind of remember what happened when they were driving through on March 16," said Marlene.
Sierra's cellphone was found Saturday night 3/4 mile from her home, but it appears it may have been thrown from a vehicle and was in the opposite direction of her school, Sobrato High.
Sierra is not forgotten by her former classmates, a sign at her high school asks that anyone with information please contact police, and the entire community anxiously waits.
"It's never something you're prepared for in such a small town. We're in kind of in a bubble here," said Krystal Thomas, a Morgan Hill business owner. "It's awful, my stomach has been hurting, I'm just praying and thinking about her mother."
"I don't see her every day and didn't notice on Friday, I wouldn't pay attention, that 'Oh, she's not there,'" said Iris Wise, a neighbor.
"We didn't hear anything, didn't see anything. Caught us by surprise," said Manuel De La Torre, a neighbor.
We learned late Monday night that Sierra's father, Steven LaMar, is a convicted sex offender; convicted in 2007 of lewd or lascivious acts with a girl under the age of 14. He spent eight months in Alameda County Jail. Monday night before reporters learned of his record, he spoke with ABC News about his last conversation with Sierra.
"I spoke to her on Thursday night. She sounded really good. She was excited about a paper she was writing and she was telling me about that," said Steven. He also told ABC News his daughter was looking forward to a visit with him in Fremont this coming weekend. "She wanted me to make a hair appointment, she was to get her hair dyed, so she was all excited about that."
He says he is innocent of any crime and pled guilty based on bad legal advice, but is still officially a sex offender. The address currently listed for LaMar on Megan's Law website is a Motel 6 - LaMar hasn't lived there for at least the past six months.
ABC7 News asked Marlene about her ex-husband's criminal record.
"I don't want to talk about that because that has nothing to do with my daughter right now. We are searching for her and that is the focus right now," said Marlene.
Despite all that information about Sierra's father, investigators say he is not a person of interest and has been cooperating fully with investigators. Family and close friends are frustrated by the distraction.
"He's not a suspect, he loves his daughter. He wants her to come home, so less focus on Sierra and just keep that attention on where it should be and bringing her home," said Tonya Miller, a family friend.
Hundreds came together for a candlelight vigil Tuesday night. The tears and emotions overflowed at the event.
"She has a lot of friends and she's always on her phone. She wouldn't leave her charger. She would've let someone know," said Alejandra Kendric, a friend.
"It's not her to be, if anything did happen, it's because she was caught off guard," said Shelly Solorio, a former cheerleading coach.
Police don't know what to think. More than 75 officers and detectives are dedicated to finding the 15-year-old.
"It's very unusual. It's been unusual since day one because we don't have the info, the factors leading to a runaway-type case," said Santa Clara Sheriffs Sgt. Jose Cardoza.
No one is giving up regardless of what happened. The flyers are still posted all over town and Midsi Sanchez attended the vigil to give friends and family hope. Sanchez was kidnapped on her way home from school in Vallejo in 2000. After three days she escaped.
"Keep your heads up. I know it's hard, but we're not going to find her if we're looking at the floor, you know what I mean? Just keep your heads up guys," said Sanchez.
Investigators say they get several tips every minute and they follow up on each and every one. There is a special email address (firstname.lastname@example.org) set up for tips on Sierra.
Both the family and investigators are hoping for the public's help solving this case. Anyone with information can contact the Anonymous Tip Line at 408-808-4431.