Port Phillip Crime Investigation Unit detectives are investigating two incidents of sexual assault that occurred in the St Kilda area late last year and early this year.
On 26 December 2022 an 18-year-old and 19-year-old were approached on the beach along Beaconsfield Parade in Middle Park by an unknown male.
He laid down on the beach near the women before exposing himself and masturbating.
On 8 January 2023 two 16-year-old girls and a 15-year-old girl were near the water on St Kilda beach along Jacka Boulevard when they noticed a male staring at them from the water.
The male walked toward them, exposing himself, and began masturbating.
In both incidents the man only stopped his behaviour when the females started filming him on their phones.
He is described as Caucasian, aged in his 50s with a solid build, bald head and grey beard.
Investigators have released footage and an image of a man they believe may be able to assist with their enquires.
Anyone who recognises the man or has information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au