A 19-year-old woman got off a Frankston-bound train at Mordialloc Railway Station with an unknown man whom she struck up a conversation with just after midnight.
The pair walked together north-east along Bear Street to a reserve, near the corner of Chute Street, when the man sexually assaulted the victim.
The offender then fled the scene and was last seen walking along Bear Street.
The victim ran back to the railway station where she raised the alarm.
The man is perceived to be of Caucasian appearance, aged in his 30s with a thin build.
He was wearing a suit without a tie at the time of the incident
Investigators have released a FACE image of a man that may assist with their enquiries.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or visit www.crimestoppersvic.com.au
