Sifting through photos of her, Brooke brags, "She's so pretty; she's so gorgeous—but she doesn't see it. And that's just it, she doesn't see how special she is. She's such a special girl, unlike anyone else."

"She's perfect. She's a perfect girl. She's so nice. She has such a creative, beautiful soul. She has the biggest heart. And then you look at her, and she's gorgeous. It's like, how can you be so perfectly made, but such a horrible disease can just destroy her and make her not see it."

PHOTOS | Have you seen Mayci?

Mayci, Brooke said, used to play soccer, is an artist, and loves nature—even her room is chalk full of plants. But underneath her beauty, immense independence and unbridled creativity, she battled a pain unseen by the naked eye. Her smiles hid her anguish.

She looked so happy in photos and seemed happy with her family. But Brooke said, she never talked about how she was feeling, so no one really saw how severe her depression was getting.

"She seemed fine. She seemed like a normal, happy girl—but she's so independent and keeps to herself, you would never know what's going on in her head."

Her mental pain began when she had just turned into a teenager and started middle school.

In 2014, the Olschewskes resided in Paulding County when she ran away for the first time. According to her sister, she was relentlessly bullied.

Mayci Olschewske

"She was being bullied really bad at school and some boys were harassing her really bad—and she has depression, so it's really hard because it clouds your judgment and you don't really know. I think she just couldn't take it and ran away," Brooke said.

Mayci was found in the woods less than a mile away from her house within hours. It was easier, Brooke said, because she was 13 and not driving yet.

She attended online school for a while to dodge her bullies.

"She just didn't want to go to school at all. Every morning, she would just cry and didn't want to go."

She really liked doing her schoolwork online, but when she started high school, she wanted to go back to a brick-and-mortar school. But it didn't work out.

"Girls are mean and boys are really mean. People were just treating her really badly," her sister said of being harassed, laughed at, teased, ignored and belittled. "She just really sweet and she's not one to be mean to anyone so she had trouble standing up for herself."

That only fueled her antagonists, Brooke said.

"When they see that it affects you really, bad, they keep doing it.”

This year, for her junior year, she and her family moved to Canton. Their parents had lived in their Paulding County home for 20 years before moving this summer.

Brooke said that Mayci was the one who instigated the family's move, eager to make new friends and start over at a new school.

"All summer she's been really excited, saying, 'I can't wait to have friends and start over,'" Brooke, a college student in Kennesaw, recalled.

Classes at Cherokee High School started on Aug. 1, but it wasn't the fresh start she had been longing for.

"She just didn't really make friends," her sister said. "She's always like, 'I just want a best friend; I want to have a really, good friend.'"

Smiles and laughter concealed the wounds inside.

"Around us, she's always so happy and laughing and just completely normal, but you would never know what is going on in her head. The depression she has to go through every day, because she just seems so fine. She doesn't really talk about what's going on with her. She always just kept to herself."

The day she left, the therapist who they had been trying to get her into see, returned their phone call to schedule an appointment. But it was too late.

"It's hard because we were in the process. We tried to get her the help she needs," Brooke said.