Content warning: This post discusses what led to a young girl’s suicide. If you or someone you know is suffering, call Lifeline on 13 11 14.

Libby Bell was 13 years old when she took her own life.

On Monday, August 28, Libby’s mum Crystal went to the shops. Libby had asked her to pick up her favourite snack. By the time her mum returned, the Adelaide schoolgirl had killed herself.

It’s a tragedy in every sense. And as her family grapples with her death and struggles to understand what could have led to it, one fact looms large in their heads: Libby was bullied.

Her uncle Clint Gow-Smith told The Project the young teen had been the subject of bullying from different groups of girls on-and-off over the past two or three years.

And of course, as is the reality for children these days, it was not contained to physical tormenting in the schoolyard. The threats, insults and other foul and vicious words written on Facebook, Instagram and Snapchat can be so much worse.

The cyber-bullying Libby faced intensified after she was the subject of a viral video in October 2016 that had spread so far it even made the evening news.

In the video, another girl can be seen walking past Libby as she sits in a restaurant and tips a drink on her.

But as much bullying as Libby was copping online and in the classroom, she put on a brave face for her family, who have described her as a smiling, bubbly girl.

And that's why they didn't see her suicide coming.

"Shocked is an understatement. It just makes no sense. I still don't want to believe it to be honest," Libby's uncle told The Project.

"She had friends sleep over on the weekend, she went to school on Monday, it just... as far as signs, no one in their right mind would have expected this.

"I just can't get my head around it. I don't think we ever will."

Still very much reeling from her loss, Libby's family are doing what they can to help prevent this from happening to other young people and other families.

Listen: Do parents have to crack down on teens? (Post continues after audio.)

They are pursuing the creation of new, tougher anti-bullying laws in South Australia, which could see perpetrators face up to 10 years jail.

They are sharing Libby's story along with this message to young people - one that other parents may also wish to impart: If you see a friend or peer being bullied, tell their parents or tell someone at the school.

As Libby's uncle puts it: "You just don't know. You could be saving someone's life."

If you or anyone you know is experiencing depression, bullying or a crisis there is help available. You can call Beyond Blue on 1300 224 636 or Lifeline on 13 11 14. Young people can also call Kids Helpline on 1800 55 1800.