Moorabool Crime Investigation Unit detectives are appealing for information about a suspicious fire at a medical clinic in Bannockburn last year.
Emergency services were called to the Geelong Road property about 1am on Sunday, December 19 after a fire was reported.
Police said the clinic was extensively damaged, with the cost estimated at $500,000.
Investigators have this week released CCTV and an image of a man they believe may be able to assist with their enquiries.
He is described as wearing a jacket, pants with reflective strips on the legs, boots and carrying a fuel container.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or make a report at crimestoppersvic.com.au.