"Assistance from the public often proves invaluable during these investigations," he said.
"We are asking for anyone who may have seen anything suspicious ... to call us," Mr Swan said.
Queensland police have gone online to ask for help, where grieving friends and family have also appealed for information.
On Facebook many mourners also pleaded for information.
Rebecca Wilson posted: "Answers are so very needed to help a lot of friends and family (including myself) with closure ... a beautiful soul so talented and gifted taken way to early!
"Everyone is missing u Tony xo I hope people understand even the slightest tiniest bit of information can help."
Jane Hunter posted: "We need to solve this crime, Tony did not deserve this, he was a beautiful man who i care about so much, and so do so many others.
"The people who did this need to be found and we need to know why they would do this, why someone would take our beautiful boy (you will be found its only a matter of time, hand yourself in!!)
"Anyone out there please ring the police with any information."