Police are investigating following an assault which occurred in Wyndham Vale last month.
Investigators have been told the 19-year-old Wyndham Vale victim was walking with her two 19-year-old friends on Eureka Drive about 11.15am when an unknown male began walking on the opposite side of the road.
It is believed the man grabbed three fist sized rocks from his orange bag and began to throw them at the group.
One of the rocks struck the victim causing her to fall.
She sustained a head injury and was transported to hospital for treatment.
The offender stopped briefly and looked back at the victim after she fell before continuing to walk along Eureka Drive.
He is perceived to be Caucasian in appearance with a shaved head, wearing a grey zip up top, dark pants and sneakers, and carrying a large orange bag.
Investigators have released images of a man that they believe may be able to assist with their enquires.
Anyone who recognises the man or with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au