Transit Crime Investigation Unit detectives are appealing for public assistance after a man performed an explicit sexual act on a Werribee line train in February.
Investigators have been told the man boarded the inbound train at Williamstown Railway Station on 18 February at 2.30pm.
The man sat opposite the 23-year-old woman where he performed a sexual act before disembarking the train at Yarraville Railway Station. Detectives have released images of a man they believe may be able to assist with their enquiries.
The man is perceived to be Caucasian in appearance, with a solid build, short dark brown hair and a distinctive dragon tattoo on his left ankle.
He was wearing a dark green hooded jumper, black and white shorts, grey sneakers and was carrying a grey backpack and blue beach chair.
Anyone who recognises the man or has information regarding the incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au