A teenager allegedly assaulted a prison riot squad officer in the aftermath of last month's destructive rampage at Banksia Hill Detention Centre.
The 18-year-old, who was a Banksia Hill detainee, allegedly bit and headbutted the man, from the Hakea Prison-based emergency support group.
The teenager has been accused of attacking the officer, who was called in to quell the trouble, while detainees were moved from the detention centre after the riot.
Detectives have charged him with two counts of assaulting a public officer.
They will allege he bit the guard on the index finger, causing it to bleed, while being taken with dozens of other youths from Banksia Hill to Hakea. The headbutt caused the guard's cheek to swell, police claim.
Investigations into the riot at the Canning Vale centre on January 20, which left up to 100 cells, computers, radios and other equipment damaged or destroyed, are continuing.
Police have yet to charge anyone over the damage.
The youth is due to appear in court next month.