Police are investigating an indecent exposure in Fitzroy that occurred in November last year.
Investigators have been told an unknown man exposed his genitals and masturbated in front of a woman about 11.35am on 17 November.
The incident took place near shrubs just south of the dolphin fountain in Fitzroy Gardens.
The woman confronted the man, who walked away from her in a northerly direction towards the dolphin fountain.
Investigators have released a facial composite of a man they believe may be able to assist with their enquiries.
He is described as being aged in his early 50s, about 180cm tall with a solid build and short grey hair.
He was wearing a light blue/grey t-shirt and green cargo shorts.
Anyone who recognises the man or with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au