When Stephanie* began chatting online to Calvin Hill, she had no idea what it would lead to.
Then aged 13, the girl from NSW's South Coast allegedly began speaking to the Chatswood man 19 years her senior via Kik, an encrypted messaging app that promotes anonymity and encourages users to "meet new people".
Calvin Hill allegedly groomed a 13-year-old girl through Kik for a period of several months
It is understood that Mr Hill allegedly claimed to be a 17-year-old boy and allegedly groomed the teen over a period of several months.
Police say Mr Hill then allegedly "met the girl in Batemans Bay and Sydney on several occasions between 2014 and 2018, where he allegedly sexually abused her."
Police began investigating Mr Hill in June this year after being informed of the alleged abuse. He was arrested last week and is now before the courts on a raft of charges.
Cyber Safety Solutions CEO and former Victorian police officer Susan McLean told The Sun-Herald that while the popularity of the app that launched in 2010 "waxes and wanes", it is still the "number one app for sex predators."
Instagram is a hub for "porn and self harm", Ms McLean saysCredit: Instagram.com
Online child sex abuse can range from a predator grooming a teen to meet them in person and sexually assaulting them to live-streaming child abuse to photographs.
Child Abuse and Sex Crimes Squad Commander Detective Superintendent John Kerlatec said that the advent of apps like Kik, Tellonym, TikTok and Whispr have "created more opportunities" for would-be child abusers.
Snapchat is among the apps that cybersafety expert Susan McLean has warned againstCredit: AFR
"Everyone has access to the internet in their back pocket. It's certainly increased the opportunities to groom. In NSW alone this year, we've seen 38 people charged," Det Supt Kerlatec said.
Those arrests - almost one per week - come from a combination of alleged predators allegedly grooming real children online and stings from Strike Force Trawler's undercover detectives.
"While some people may downplay it [the use of undercover officers], we see the scenarios - those people turn up with condoms or a motel room booked".
Police see the same pattern of behaviour repeated by child sex offenders, Det Supt Kerlatec said.
Video sharing app TikTok Credit: Alamy
"They build rapport and ingratiate themselves. They could be pretending to be someone that you'd be pleased to talk to, but it's not - it's someone with nefarious intentions.
"The conversation will lead to images and then more graphic images, images that are sexualised."
Parents need to be educated by their children on the ever-changing world of online communication, Det Supt Kerlatec said.
"The people who are on these devices day in day out are far more educated than their parents. Parents should be taught by their kids about what they're looking at and who they are talking to, then pose some scenario questions," he said.
Ms McLean said that parents needed to follow the age restrictions on apps, and only allow children over 13 to use them.
Designed as a chat app for gamers, Discord is increasingly being misused
"It's so much easier to trick little children into doing stuff," she said.
While online child sex offenders are predominantly - but not exclusively - men, there is no typical offender, Det Supt Kerlatec said.
"There is no set age, demographic, occupation or socioeconomic background".
Australian eSafety Commissioner Julie Inman Grant said that the trend towards encrypted apps - whose messages cannot be intercepted - had created further challenges of child protection.
Likee is growing in popularity with children - and those who would sexually abuse them
"[It] is making the job of investigators into serious online child sexual abuse more difficult. It also creates a secondary Dark Web in which platforms can absolve themselves of responsibility for safety."
* Stephanie is a pseudonym used by The Sun-Herald to comply with legislation prohibiting the identification of child victims of crime.
The apps most popular with child predators
TikTok - A short-form video sharing app that has been downloaded over one billion times. A BBC investigation earlier this year found that while the Chinese-owned app deleted sexualised content directed at children, the users who posted it were allowed to remain on the platform.
Instagram - Owned by Facebook, the photo sharing app is popular with adults and teens alike. Ms McLean's says that Instagram is not "dogs and cats", it's "self-harm and porn".
Snapchat - The self-destructing photo app has UK police investigating three cases of online child abuse per day, according to a Sunday Times report.
Discord - Developed as a means for gamers to talk to each other as they played, Ms McLean says she has had an "explosion" of reports about the app in the past few months.
Likee - The video sharing app that aims to topple Tik Tok is increasingly popular with teens, and has recently introduced a parental control feature.