Australian police say more than 150 people could have fallen victim to a suspected paedophile who posed online as Justin Bieber.
The man - who's a lecturer in Brisbane is accused of using Facebook and Skype to get young people to send him explicit photos.
He's been charged with more than 900 child sex offences.
Social media expert Daniel Angus says it's incredibly easy to pose as someone you're not these days
"I think for parents the advice I would give is to have the conversation with your children, that not everyone online is who they say they are, and to keep technology in the open."