Sexual Crimes Squad detectives are appealing for public assistance after a woman was sexually assaulted at a music festival in St Kilda on 27 September.
Police have been told a 20-year-old woman was dancing in a crowd of people with an unknown man about 7pm.
The woman made her way to nearby toilets where she was sexually assaulted by the same man.
The man left and the woman reported the matter and was taken to hospital for treatment.
The offender is described as Caucasian in appearance, aged between 21-23 years-old with a slim build and short red-brown coloured hair and freckles.
He was wearing dark clothing and possibly went by the name Adam or Toby.
Detectives have released a computer-generated image of a man they believe may be able to assist with their enquiries.
Investigators are keen to speak to anyone that may have witnessed the man at the event or who has any information to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.ua