Transit Crime Investigation Unit detectives are investigating after a woman was sexually assaulted while travelling on a train earlier this year.
Investigators have been told an 18-year-old woman was travelling on a V/Line train when an unknown male boarded at Pakenham Railway Station about 2.30pm on 10 May.
The male sat down beside the woman and began talking to her, saying she was "pretty" before inappropriately touching her.
The woman got off the train while the man stayed onboard and it is not known where he disembarked.
The man was perceived to be of African appearance and described as being in his 40s or 50s and about 190cm tall.
He was wearing a green camouflage jacket and matching pants.
Investigators have released images of a man they believe may be able to assist with their enquiries.
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
