Linda Trevan said that though Cassidy reported the gang rape to police, she never made a victim statement, so they weren't able to press charges against her bullies.
“Cass was scared to make a formal statement for fear of retaliation from the gang, and she also was worried reliving it would ‘push her over the edge’,” she told 9News.
Linda moved Cassidy to different schools, but she continued to have PTSD and panic attacks from the crime.
The bullies continued to harass Cassidy over the phone and social media, and eventually, Cassidy committed suicide in December 2015.
She wrote about her daughter's suicide in an emotional Facebook post in January this year, saying that it was a direct result of the bullying.
“I helplessly watched my precious child wither away before my eyes, mentally & physically, until she rarely got out of bed, until she could no longer take the pain and torment you caused her,” she wrote.
“I know who you are, you know who you are, and the police know who you are. I hope the knowledge of what you did haunts you for the rest of your lives, and one day, if you are lucky enough to have children of your own ... remember what you did to my precious only baby, and imagine how you'd feel if someone did that to your baby.
“Cassy was my world, she still is and she always will be. But now I have nothing, and I'm still trying to find a reason to go on without her.”
Linda urged bullies to think before they act.
“I want the bullies out there to know that it’s not just a game. It costs lives.”