A 42-year-old Queensland man faces more than 900 counts of child sex offences, after police discovered he'd solicited explicit photos from minors by posing as online Justin Bieber. The prosecutor will allege Gordon Douglas Chalmers, a law lecturer at Queensland University of Technology, used both Facebook and Skype to trick young fans.Chalmers was first arrested over a number of sex offences back in November last year, after a tip-off from US and German police. At the time of his arrest, police opposed bail citing his "rapacious appetite" for contacting children could lead to more offences. It's alleged Chalmers "refused" to grant investigators access to his social media accounts.However, after a search of his computer this week, Chalmer's charge sheet was expanded to 931 counts—including making child exploitation material, using a carriage service to procure person under 16, rape, and the indecent treatment of children. Police allege these offences date back to 2007.Detective Inspector Jon Rouse said the case highlights how vulnerable children are online, because of "the global reach and skill that child sex offenders have to groom and seduce victims.""The fact that so many children could believe that they were communicating with this particular celebrity highlights the need for a serious rethink about the way that we as a society educate our children about online safety," Detective Rouse said in a statement. "The breadth of offences committed in this instance are frankly horrendous and I want to recognise the efforts and commitment of the investigative team at Taskforce Argos to keeping children safe."Chalmers is set to next appear in Brisbane Magistrates Court on April 6.