Transit Crime Investigation Unit detectives are seeking a third man following an armed robbery at Wyndham Vale train station on Friday 3 July.
A teenager was followed into the toilets by four males where he was assaulted with a knife and robbed of his phone and Air Pods about 3.50pm.
Police arrested two teens, aged 16 and 17 last month in relation to the incident and they have each been charged with armed robbery, unlawful assault, false imprisonment and make threats to kill.
The 17-year-old was remanded into custody and subsequently bailed by a Magistrate to appear at a children’s court at a later date.
The 16-year-old remains in custody to appear at a children’s court at a later date.
Detectives are now seeking to identify the third males involved and have released CCTV images of a person they wish to speak to.
He is perceived to be African in appearance and aged in his early 20s.
He was wearing a dark grey hooded jacket over a light grey hoodie and light track pants.