When Lori Drew's 13-year-old daughter, Sarah, told her that her friend Megan, 13, was spreading rumours about her at school, Lori decided to step in.
But instead of having a word to Megan's parents, Lori decided to get even.
After seeking the help of an 18-year-old employee, she created a Myspace account and pretended to be a 16-year-old boy named Josh Evans.
She used the account to befriend Megan and began sending her flirtatious messages. Megan was smitten.
But not long after, Lori's tone changed and she started sending cruel messages and posting public bulletins about Megan on the website.
The last message 'Josh' sent to Megan read: You are a bad person and everybody hates you. Have a s---ty rest of your life.
The world would be a better place without you.
Megan was distraught and responded saying: You're the kind of boy a girl would kill herself over.
Tragically, Megan took her life not long after she received the messages.
The police found out about Lori's deception and she was convicted of accessing a computer without authorisation in order to inflict emotional distress.
Lori was acquitted of all of her charges due to the vagueness of the laws.
The public nature of the case made politicians realise laws needed to be changed to protect victims of cyber bullying.
Breck Bednar, 14, was a clever student from Essex, England.
He was fascinated by computers, and after doing his homework, played online games with his school mates and a boy named Lewis Daynes, who owned the internet server they all played on.
He claimed to be a 17-year-old computer engineer, running a multimillion dollar company. Breck's mum Lorin LaFave was worried about her son's growing relationship with Lewis.
But Breck insisted he could offer fantastic job opportunities.
Lewis had even encouraged him not to finish school so he could start work. Lorin offered to go with Breck to meet him, but Lewis was always busy at the last minute.
Suspicious, Lorin called police and asked them to do a background check on Lewis. They never did. Meanwhile, Lewis had sent Breck a secret phone so they could communicate.
He told him that he was dying, and wanted to hand the company over to Breck, only if he could come to his flat for training.
Breck was excited when he arrived but then Lewis' real motive became clear.
He stabbed Breck and slit his throat, before sending photos of his body to the other gaming group members.
Now, police have created a film called Breck's Last Game which aims to educate and protect boys from online grooming.
In the sleepy town of Mountain City, Tennessee, Billy Payne, 36, and his fiance Billie-Jean Hayworth, 23, were murdered in their home, their seven-month-old son still alive and squirming in his dead mother's arms.
The incident shocked the tight-knit town and was caused by another unlikely resident Jenelle Potter, 34, a tall, softly-spoken girl who still lived with her parents.
Jenelle didn't have any friends and used social media as her connection with the outside world.
One day Tracy, a clerk at the local pharmacy, took pity on her and invited her to hang out with her friends and brother, Billy Payne. She became infatuated with him.
Tracy also introduced Jenelle to her cousin Jamie Curd, and the pair started a secret relationship.
Although it seemed like Jenelle's social life was blossoming, she was receiving cruel messages on her Facebook page. She told her parents, Barbara and Marvin, that Billy's fiance Billie-Jean was bullying her, jealous of Jenelle's good looks.
Eventually, Jenelle deleted her former friends on Facebook but then, Billy and Billie-Jean were found dead.
A day after the murders, the County Sherriff's Department talked to Jenelle, Barbara and Marvin due to their Facebook feud with the couple.
During the interview, Jenelle's secret relationship with Jamie became known. The sheriffs then conducted a polygraph test on Jamie to see if he knew about the murder. "Is the CIA here?" he asked.
Jamie said he'd been in contact with a man named Chris from the CIA.
Chris had told him it was his job to protect Jenelle at all costs. But Chris wasn't real.
Jenelle had posed as a CIA agent, convincing her boyfriend and parents to murder her so-called bullies.
The couple were both shot, while Billie-Jean was still holding their son, Tyler, who survived.
Police cottoned on when they examined messages supposedly sent by Chris, all of which contained similar grammatical errors made by Jenelle.
Barbara and Jenelle were sentenced to life in prison for planning the deaths of the couple. Marvin was sentenced to two consecutive life sentences and Jamie was sentenced to 25 years in prison.