Carly thought she'd found her dream boyfriend online. Instead, she was talking to her killer.

Carly Ryan was loving, caring, kind and funny. She was her mother, Sonya's "special girl."

In 2006, the South Australian teenager thought she had met her dream boyfriend online. But he never existed.

Over 18 months, Carly exchanged hundreds of messages and calls with someone she thought was Brandon Kane, an 18-year-old musician from Melbourne.

But Brandon wasn't real.

Listen: How the murder of Carly Ryan sparked a mother's mission against online predators. Post continues below.

Carly was really speaking to Garry Francis Newman, a 50-year-old predator living in Victoria.

Eventually, Newman flew out to meet Carly — posing as Brandon's father.

He tried to seduce her. When that failed, he lured Carly to a fatal meeting.

In February 2007, Newman took Carly to a secluded beach at Port Elliott, South Australia and murdered her.

She was only 15-years-old.

Carly was 15 when she was murdered. Image: Supplied.

Carly's mother, Sonya Ryan, said the day she learned of her daughter's death was like "stepping into a horror movie."

"She hadn't turned up at a friend's house as she was supposed to, and so we were in this kind of panic," she told Mamamia's True Crime Conversations.

"When the police started rolling in the back door, I just thought, 'This seems a bit strange.' Even when they started coming in the door, I saw one officer had a tear running down his face. In that moment, I was like, 'What on earth is going on?'"

Sonya said there was "no preparation" for the words that came out of the officer's mouth.

"This crime type had never happened in Australia before," she explained.

"There's no way to prepare for hearing that kind of news from a police officer. So detectives walked in and said that they'd found the body of a girl matching the description of Carly, and I just remember thinking, 'What do you mean a body?'

"You go into incredible shock, and every part of you, I guess, really dissolves on the spot. You're conditioning, layers of yourself, just kind of fall away and you're left in a very raw state.

"It was kind of stepping into a horror movie."

That was the "beginning of everything," as Sonya described it.

Next came identification, and as police honed in on Newman as a suspect, the horrible reality of what happened to Carly sank in.

Carly believed she was talking to Brandon, an 18-year-old who adored her. Image: Supplied.

Sonya remembered meeting Newman as he posed as Brandon's father.

Call it a mother's instinct, but she knew something was off about him.

"I kicked him out of our home when I realised that something wasn't quite right. Did my mind go to a murderer? Absolutely not," she said.

"My mind went to somebody's creepy dad, who was acting a bit strange."

But because the internet was in its early days, Sonya had no idea about the lurking danger.

"I felt like Carly was like a lamb to the slaughter. Like she was just so open and loving, and loved everybody, believed in everyone," Sonya said.

"And that's what he used to manipulate her, to get her to meet him, without telling me. He used her kind nature, her loving nature, her forgiving nature, to lure her."

One of the "cruellest" aspects of what happened to Carly, according to her mother, was the fact she thought she was talking to someone who adored her.

"This wasn't an overnight thing. He'd check in, 'how's your homework going?' 'How's your mum,' 'how's your family?' Like being invested in her day-to-day life, encouraging her," Sonya said.

"These are the tactics that we now know criminals use to groom children. But back then, I had absolutely no idea."

After being found guilty of murder by a jury, Newman was sentenced to life in prison with a 29-year non-parole period on 31 March 2010.

'This is a pandemic.'

Sonya wasn't able to save her daughter, but she's resolved to protect other children from online predators.

"From the latest research, over 350 million children are exploited online every single year. This is a pandemic in itself and as a community, we have to face this," she explained.

"I couldn't save her, but what I can do is save others from the same fate, from the same level of suffering. And that is a promise I made to her, and it's one I intend to keep."

Sonya founded the Carly Ryan Foundation in 2010 and after a tireless crusade, "Carly's Law" was passed by Federal Parliament in 2017.

Carly Ryan was loving and caring. Kind and funny. Image: Supplied.

Authored by Sonya, the legislation makes it a criminal offence for someone to lie about their identity and age online to a minor under the age of 16.

"The fallout from losing her was horrific and just the circumstances in which it happened were, you know, really, I just still today, don't have the words for it," Sonya said.

"I just have to focus my whole attention to the work, the end focus, and again, coming back to thinking about what Carly would want me to do.

"That is to make sure that what happened to her doesn't happen to another innocent child. For no other parent to have to stand behind a curtain and identify their beaten child."

Feature image: Supplied.