Transit Crime Investigation Unit detectives are appealing for public assistance following a sexual assault on a bus in Scoresby in April.
It is understood a man sexually assaulted a female victim on the Frankston-bound 901 bus about 3.40pm on Monday, 29 April.
The man, perceived to be Indian Sub-Continental in appearance, of medium build with dark hair, got off the bus at Dandenong Railway Station a short time later.
Investigators have released an image of a man who they believe may be able to assist with their enquiries.
The man was seen wearing black puffer jacket, light blue jeans and a red baseball cap.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au