Around 8am on Thursday 23 May 2019, a 13-year-old girl secured her bicycle to a stand at a shopping centre on Forrest Lakes Drive Thornlie.
A short time later, a man approached the bicycle, removed the device and rode away.
The bicycle is described a maroon coloured BMX Mongoose with a grey seat and pink handlebars.
Police have released a CCTV image of a man who they believe may be able to assist them with their investigation.
The man is described as: Light skinned, 20-30 years of age and a medium build. He was wearing a hooded top, grey pants and a distinctive multi coloured cap under the hoodie.
If you have any information about the identity of this man or details of this offence please contact Crime Stoppers on 1800 333 000 or report online at www.crimestopperswa.com.au. You can remain anonymous if you wish and rewards are available once charges are laid. Please quote Reference Number 9280.