Detectives from the Dandenong Sexual Offence and Child abuse Investigation Team are investigating a sexual assault at a shopping centre in Narre Warren.
Investigators have been told a 22-year-old woman was working in a shop when a man approached her and touched her inappropriately at 3.40pm on 31 March.
The man then left the store and walked around the shopping centre for a short time before leaving.
Police believe the man may have been involved in previous similar incidents in 2012 and 2013.
He is described as Caucasian in appearance, in his 20s, with a slim build, blue eyes, short blonde hair and a fair complexion.
He was wearing a dark-blue long-sleeved shirt with a white logo, light-blue shorts and black thongs.
Investigators have released CCTV images and a computer-generated image of a man police believe may be able to assist with their enquiries.
Anyone who recognises this man or who may have witnessed this incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au