Melbourne Sexual Offences and Child Abuse Investigation Team detectives are investigating an indecent assault at a bowling alley in Melbourne on 1 November.
Investigators have been told a man entered the toilets at the centre on Latrobe Street about 12.50pm.
The man then masturbated in front of a 15-year-old boy before fleeing out of the toilets.
The man is described as aged 40-50-years-old, solid build with grey hair.
Investigators have released images of a man they believe may be able to assist with their enquiries.
Any witnesses or anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.