Transit Crime Investigation Unit detectives are investigating after a man exposed his buttocks while travelling on a train earlier this year.
Investigators have been told two female youths were travelling on the Frankston line when they were approached by an unknown man about 6.50pm on Saturday 20 March.
It is understood the man boarded the train at Caulfield, exposed hit buttocks to the girls and made inappropriate comments towards them before getting off the train at Bentleigh about 7pm.
Investigators have released images and CCTV footage of a man they believe can assist with their enquiries.
He is perceived to be Caucasian, approximately 35-years-old, about 180cm tall with a shaved head, medium build and a tattoo on his right arm.
He was wearing light blue jeans, a grey t-shirt, white runners and had a blue suitcase.
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.