Transit Crime Investigation Unit detectives are appealing for public assistance after a man performed a lewd act in Endeavour Hills last month.
Police have been told the man engaged in the lewd act in the presence of young woman on the route 845 bus between Linden Park and Endeavour Hills about 12:15pm on Monday, 14 October.
The man departed the bus at the corner of Hanna Drive and Reema Boulevard.
The woman was not physically injured.
Investigators have released images of a man they believe may be able to assist with their enquiries.
He is perceived to be Middle Eastern in appearance, between 30 and 45 years of age, is bald and has a brown moustache and beard.
He was wearing black sunglasses, a green or blue "Puma" t-shirt and light-coloured jeans.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au
