Melbourne Embona Taskforce detectives are appealing for public assistance following a robbery in Melbourne in February.
Investigators have been told a man was approached by four males in a stairwell at a Swanston Street shopping centre about 7.50pm on 22 February.
One of the males punched the victim and stole his phone before a second male made demands for his sunglasses and cigarettes.
The group then fled on foot.
The victim, a 27-year-old Melbourne man, did not require medical treatment.
Detectives have released images of four males and a composite image of a man who they believe will be able to assist with their enquiries.
The first male, who is shown in the composite image, is perceived to be African in appearance with a slim build and had redness in the eye.
He was wearing a blue and white Nike hoodie, black Adidas trackpants with white stripes down the side and white runners.
The second male is perceived to be African in appearance with heavy build and a moustache.
He was wearing a black cap with white writing on it, black long sleeve hoodie, navy puffer vest, grey tracksuit pants, black runners and carrying a black shoulder bag.
The third male is perceived to be African in appearance with a solid build and black short shaved hair.
He was wearing a black tracksuit, white t-shirt, black and white runners and carrying a black bag worn across his shoulder.
The fourth offender is perceived to be African in appearance with a slim build, short black hair.
He was wearing a Nike tracksuit and black runners.
The investigation remains ongoing and anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au