Transit Crime Investigation Unit detectives are hoping to identify three males following an armed robbery on a city bound train on 31 December 2019.
Police have been told three males approached a male passenger while in transit between Yarraman Railway Station and Sandown Park Railway Station about 5pm.
The group threatened the 16-year-old victim and made demands for his Nike jacket and cash.
One of the male offenders, who was carrying a bum bag, opened it and threatened to use a large knife inside.
The victim complied and the offenders took off with his jacket and cash.
The group got off at Springvale Railway Station and boarded a Chelsea 902 bus.
Police have released images of three males they believe may be able to assist with their investigation.
One male is perceived as African in appearance, thin build, and was wearing a black Nike jacket, ripped jeans and a black cap.
The second male is perceived as African in appearance, solid build and was wearing a black hooded jacket and black shorts.
The third male is perceived as African in appearance, thin build, and was wearing a Nike vest.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au