Former police chief Neil Comrie and the Department of Health and Human Services will appear before the Victorian parliamentary inquiry into youth justice.
Mr Comrie, the former chief commissioner of Victoria Police, was called in to review the system after a series of riots in Melbourne’s Parkville youth justice centre in November.
He is on Wednesday expected to present evidence from his report, released earlier this year, which found violence and disturbances became "commonplace" as teens exploited infrastructure weaknesses in Victoria’s youth justice system.
Inmates smashed through ceilings, climbed onto roofs and threatened staff with makeshift weapons during the November riots.
"It is clear that a defining point has been reached in the long history of youth justice in Victoria," Mr Comrie wrote in the report.
"Infrastructure, policy and systems that were designed and built for a different era have proven to be incapable of delivering the imperative of a safe and secure youth justice system in 2016/17."
Part two of Mr Comrie’s review was released in March, making 11 recommendations including better training for staff.
DHHS representatives are also due to appear at inquiry.
Its youth justice responsibilities were transferred to the Department of Justice and Regulation in March following unrest across the system.
The sector has been under massive scrutiny following the riots and a mass escape from the Malmsbury youth justice centre in January.
Riots also rendered parts of Parkville uninhabitable so the government moved some detainees to a unit in the adult Barwon prison.
That decision sparked several court challenges – which ruled housing teen inmates in that facility was unlawful.
Wednesday’s hearing starts at 10am and will also hear from the Human Rights Law Centre, the Children’s Court of Victoria and the Crime Statistics Agency.