Police have laid fresh charges as part of their investigation into the death of Perth teenager Cassius Turvey over the alleged kidnapping and assault of another teenager.
Police allege the 15-year-old boy was kidnapped and assaulted days before a separate incident which led to the death of Cassius in Perth's eastern suburbs.
It's alleged the boy was punched, kicked and stabbed during an attack and held against his will at a house, before being released.
Four people have been charged over the alleged kidnapping, which occurred in the eastern Perth suburb of Swan View on October 9.
Police allege about 4:40pm on that date, Ethan Robert MacKenzie, Jack Brearley and Mitchell Colin Forth chased the child and caught him in the driveway of a house on Dagmar Way.
Mr MacKenzie, 18, from the nearby suburb of Bellevue, appeared in the Midland Magistrates Court on Wednesday.
The court was told it was alleged the victim was pushed to the ground and punched and kicked, with Mr Brearley allegedly "stomping" on the child's head.
Police say Mr MacKenzie then stabbed the victim in the stomach.
The court heard Mr Forth held the boy in a headlock and Mr Brearley punched him in the face.
He was then allegedly put in the back of a silver hatchback being driven by another person that was also carrying two more juvenile boys wearing ski masks.
Claims of 'mistaken identity'
The court heard the occupants of the car raised concerns the victim was not the right person and it was a case of mistaken identity.
He was then allegedly taken to a house, robbed and then released along with threats of violence if he told anyone what happened.
The court heard Mr Brearley was on drugs at the time and he could not remember anything.
In court on Wednesday Mr MacKenzie initially applied for bail but following a short recess with his lawyer that was withdrawn.
The police prosecutor opposed bail on the basis Mr MacKenzie was already on bail when he carried out the alleged Swan View assault.
The court was told that bail related to breaching a violence restraining order.
It also heard he was facing separate charges of armed robbery and common assault.
Police say he used the same knife he used to stab the 15-year-old victim in an armed robbery.
Mr MacKenzie's mother appeared to be in court on Wednesday, with her son calling out "come on, let's go to Hakea" and "bye mum" as he was led away.
Three of the people charged over the incident, including Mr Brearley and Mr Forth, were already facing charges over the assault and death of Cassius.
A woman who had been charged over the death of Cassius — a 20-year-old from Herne Hill — is also charged over the alleged kidnap.
Cassius died in hospital on October 23, ten days after the initial incident.
